(As extracted from Scopus database with research key “DCMS”)

2023

  • Electronic structure simulation of thin silicon layers: Impact of orientation, confinement, and strain
    • T. Joseph, F. Fuchs, J. Schuster
    • Physica E: Low-Dimensional Systems and Nanostructures 146, 115522 (2023)
    • DOI   Abstract  

      Silicon-on-insulator is a key technology to support the continuation of Moore’s law. This publication investigates the impact of orientation, confinement, and strain on the electronic structure of thin silicon slabs using density functional theory. The comparative study of low-index orientations demonstrates that confinement not only widens the band gap but also transforms the band gap type. For thin silicon layers, strain can alter band gap and band gap type, too. By comparing our findings for different crystal orientations, we demonstrate that the consideration of the electronic structure of strained and confined silicon is of high relevance for modelling actual devices. © 2022 Elsevier B.V.

      @ARTICLE{Joseph2023,
      author={Joseph, T. and Fuchs, F. and Schuster, J.},
      title={Electronic structure simulation of thin silicon layers: Impact of orientation, confinement, and strain},
      journal={Physica E: Low-Dimensional Systems and Nanostructures},
      year={2023},
      volume={146},
      doi={10.1016/j.physe.2022.115522},
      art_number={115522},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85141923974&doi=10.1016%2fj.physe.2022.115522&partnerID=40&md5=05a4a64b6523313c5c3588e87973cba4},
      affiliation={Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, 01328, Germany; Center for Microtechnologies (ZFM), Chemnitz University of Technology, Chemnitz, 09111, Germany; Fraunhofer Institute for Electronic Nano Systems (ENAS), Technologie-Campus 3, Chemnitz, 09126, Germany; Center for Advancing Electronics Dresden (CFAED), TU Dresden, Dresden, 01062, Germany; Forschungsfabrik Mikroelektronik Deutschland (FMD), Berlin, 10178, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Silicon-on-insulator is a key technology to support the continuation of Moore's law. This publication investigates the impact of orientation, confinement, and strain on the electronic structure of thin silicon slabs using density functional theory. The comparative study of low-index orientations demonstrates that confinement not only widens the band gap but also transforms the band gap type. For thin silicon layers, strain can alter band gap and band gap type, too. By comparing our findings for different crystal orientations, we demonstrate that the consideration of the electronic structure of strained and confined silicon is of high relevance for modelling actual devices. © 2022 Elsevier B.V.},
      author_keywords={Confinement; Density functional theory; Electronic structure; Silicon; Strain},
      keywords={Crystal orientation; Electronic structure; Energy gap; Silicon on insulator technology, Comparatives studies; Confinement; Density-functional-theory; Electronic.structure; Key technologies; Moore Law; Silicon on insulator; Silicon slabs; Structure simulations; Thin silicon layers, Density functional theory},
      correspondence_address1={Fuchs, F.; Fraunhofer Institute for Electronic Nano Systems (ENAS), Technologie-Campus 3, Germany; email: florian.fuchs@enas.fraunhofer.de},
      publisher={Elsevier B.V.},
      issn={13869477},
      coden={PELNF},
      language={English},
      abbrev_source_title={Phys E},
      document_type={Article},
      source={Scopus},
      }

2022

  • Hydrodynamic phase field crystal approach to interfaces, dislocations, and multi-grain networks
    • V. Skogvoll, M. Salvalaglio, L. Angheluta
    • Modelling and Simulation in Materials Science and Engineering 30, 084002 (2022)
    • DOI   Abstract  

      We derive a phase field crystal model that couples the diffusive evolution of a microscopic structure with the fast dynamics of a macroscopic velocity field, explicitly accounting for the relaxation of elastic excitations. This model captures better than previous formulations the dynamics of complex interfaces and dislocations in single crystals as well as grain boundary migration in poly-crystals where the long-range elastic field is properly relaxed. The proposed model features a diffusivity that depends non-linearly on the local phase. It induces more localized interfaces between a disordered phase (liquid-like) and an ordered phase, e.g., stripes or crystal lattices. For stripes, the interface dynamics are shown to be strongly anisotropic. We also show that the model is able to evolve the classical PFC at mechanical equilibrium. However, in contrast to previous approaches, it is not restricted to a single-crystal configuration or small distortions from a fixed reference lattice. To showcase the capabilities of this approach, we consider a few examples, from the annihilation of dislocation loops in a single crystal at mechanical equilibrium to the relaxation of a microstructure including crystalline domains with different orientations and grain boundaries. During the self-annihilation of a mixed type dislocation loop (i.e., not shear or prismatic), long-range elastic effects cause the loop to move out of plane before the annihilation event. © 2022 IOP Publishing Ltd.

      @ARTICLE{Skogvoll2022,
      author={Skogvoll, V. and Salvalaglio, M. and Angheluta, L.},
      title={Hydrodynamic phase field crystal approach to interfaces, dislocations, and multi-grain networks},
      journal={Modelling and Simulation in Materials Science and Engineering},
      year={2022},
      volume={30},
      number={8},
      doi={10.1088/1361-651X/ac9493},
      art_number={084002},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85139997683&doi=10.1088%2f1361-651X%2fac9493&partnerID=40&md5=0a565eb317fff12c636341a66b4249d2},
      affiliation={PoreLab, Njord Centre, Department of Physics, University of Oslo, PO Box 1048, Oslo, 0316, Norway; Institute of Scientific Computing, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany},
      abstract={We derive a phase field crystal model that couples the diffusive evolution of a microscopic structure with the fast dynamics of a macroscopic velocity field, explicitly accounting for the relaxation of elastic excitations. This model captures better than previous formulations the dynamics of complex interfaces and dislocations in single crystals as well as grain boundary migration in poly-crystals where the long-range elastic field is properly relaxed. The proposed model features a diffusivity that depends non-linearly on the local phase. It induces more localized interfaces between a disordered phase (liquid-like) and an ordered phase, e.g., stripes or crystal lattices. For stripes, the interface dynamics are shown to be strongly anisotropic. We also show that the model is able to evolve the classical PFC at mechanical equilibrium. However, in contrast to previous approaches, it is not restricted to a single-crystal configuration or small distortions from a fixed reference lattice. To showcase the capabilities of this approach, we consider a few examples, from the annihilation of dislocation loops in a single crystal at mechanical equilibrium to the relaxation of a microstructure including crystalline domains with different orientations and grain boundaries. During the self-annihilation of a mixed type dislocation loop (i.e., not shear or prismatic), long-range elastic effects cause the loop to move out of plane before the annihilation event. © 2022 IOP Publishing Ltd.},
      author_keywords={dislocations; hydrodynamics; interfaces; phase-field crystal},
      keywords={Annihilation; Crystal orientation; Dislocations (crystals); Grain boundaries; Hydrodynamics; Shear flow; Velocity, Dislocation; Dislocation loop; Fast dynamics; Grain networks; Interface dislocation; Mechanical equilibrium; Microscopic structures; Multi-Grain; Phase-field crystal models; Phase-field crystals, Single crystals},
      correspondence_address1={Skogvoll, V.; PoreLab, PO Box 1048, Norway; email: vidarsko@uio.no},
      publisher={Institute of Physics},
      issn={09650393},
      coden={MSMEE},
      language={English},
      abbrev_source_title={Modell Simul Mater Sci Eng},
      document_type={Article},
      source={Scopus},
      }

  • Tunable chirality of noncentrosymmetric magnetic Weyl semimetals in rare-earth carbides
    • R. Ray, B. Sadhukhan, M. Richter, J. I. Facio, J. van den Brink
    • npj Quantum Materials 7, 19 (2022)
    • DOI   Abstract  

      Even if Weyl semimetals are characterized by quasiparticles with well-defined chirality, exploiting this experimentally is severely hampered by Weyl lattice fermions coming in pairs with opposite chirality, typically causing the net chirality picked up by experimental probes to vanish. Here, we show this issue can be circumvented in a controlled manner when both time-reversal- and inversion symmetry are broken. To this end, we investigate chirality disbalance in the carbide family RMC2 (R a rare-earth and M a transition metal), showing several members to be Weyl semimetals. Using the noncentrosymmetric ferromagnet NdRhC2 as an illustrating example, we show that an odd number of Weyl nodes can be stabilized at its Fermi surface by properly tilting its magnetization. The chiral configuration endows a topological phase transition as the Weyl node transitions across the Fermi sheets, which triggers interesting chiral electromagnetic responses. Further, the tilt direction determines the sign of the resulting net chirality, opening up a simple route to control its sign and strength. © 2022, The Author(s).

      @ARTICLE{Ray2022,
      author={Ray, R. and Sadhukhan, B. and Richter, M. and Facio, J.I. and van den Brink, J.},
      title={Tunable chirality of noncentrosymmetric magnetic Weyl semimetals in rare-earth carbides},
      journal={npj Quantum Materials},
      year={2022},
      volume={7},
      number={1},
      doi={10.1038/s41535-022-00423-z},
      art_number={19},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85124768657&doi=10.1038%2fs41535-022-00423-z&partnerID=40&md5=bd6d39ece036354a70d6c91b739b22c1},
      affiliation={Institute for Theoretical Solid State Physics, Leibniz IFW Dresden, Helmholtzstr. 20, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Institute of Theoretical Physics, Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={Even if Weyl semimetals are characterized by quasiparticles with well-defined chirality, exploiting this experimentally is severely hampered by Weyl lattice fermions coming in pairs with opposite chirality, typically causing the net chirality picked up by experimental probes to vanish. Here, we show this issue can be circumvented in a controlled manner when both time-reversal- and inversion symmetry are broken. To this end, we investigate chirality disbalance in the carbide family RMC2 (R a rare-earth and M a transition metal), showing several members to be Weyl semimetals. Using the noncentrosymmetric ferromagnet NdRhC2 as an illustrating example, we show that an odd number of Weyl nodes can be stabilized at its Fermi surface by properly tilting its magnetization. The chiral configuration endows a topological phase transition as the Weyl node transitions across the Fermi sheets, which triggers interesting chiral electromagnetic responses. Further, the tilt direction determines the sign of the resulting net chirality, opening up a simple route to control its sign and strength. © 2022, The Author(s).},
      correspondence_address1={Ray, R.; Institute for Theoretical Solid State Physics, Helmholtzstr. 20, Germany; email: r.ray@ifw-dresden.de; van den Brink, J.; Institute for Theoretical Solid State Physics, Helmholtzstr. 20, Germany; email: j.van.den.brink@ifw-dresden.de},
      publisher={Nature Research},
      issn={23974648},
      language={English},
      abbrev_source_title={npj Quantum Mater.},
      document_type={Article},
      source={Scopus},
      }

  • Toward Coarse-Grained Elasticity of Single-Layer Covalent Organic Frameworks
    • A. Croy, A. Raptakis, D. Bodesheim, A. Dianat, G. Cuniberti
    • Journal of Physical Chemistry C 126, 18943-18951 (2022)
    • DOI   Abstract  

      Two-dimensional covalent organic frameworks (2D COFs) are an interesting class of 2D materials since their reticular synthesis allows the tailored design of structures and functionalities. For many of their applications, the mechanical stability and performance is an important aspect. Here, we use a computational approach involving a density-functional based tight-binding method to calculate the in-plane elastic properties of 45 COFs with a honeycomb lattice. Based on those calculations, we develop two coarse-grained descriptions: one based on a spring network and the second using a network of elastic beams. The models allow us to connect the COF force constants to the molecular force constants of the linker molecules and thus enable an efficient description of elastic deformations. To illustrate this aspect, we calculate the deformation energy of different COFs containing the equivalent of a Stone-Wales defect and find very good agreement with the coarse-grained description. © 2022 American Chemical Society. All rights reserved.

      @ARTICLE{Croy202218943,
      author={Croy, A. and Raptakis, A. and Bodesheim, D. and Dianat, A. and Cuniberti, G.},
      title={Toward Coarse-Grained Elasticity of Single-Layer Covalent Organic Frameworks},
      journal={Journal of Physical Chemistry C},
      year={2022},
      volume={126},
      number={44},
      pages={18943-18951},
      doi={10.1021/acs.jpcc.2c06268},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85141809913&doi=10.1021%2facs.jpcc.2c06268&partnerID=40&md5=8b2bd720d0f43fe11265ec5be3b4c32f},
      affiliation={Institute of Physical Chemistry, Friedrich Schiller University Jena, Jena, 07737, Germany; Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Two-dimensional covalent organic frameworks (2D COFs) are an interesting class of 2D materials since their reticular synthesis allows the tailored design of structures and functionalities. For many of their applications, the mechanical stability and performance is an important aspect. Here, we use a computational approach involving a density-functional based tight-binding method to calculate the in-plane elastic properties of 45 COFs with a honeycomb lattice. Based on those calculations, we develop two coarse-grained descriptions: one based on a spring network and the second using a network of elastic beams. The models allow us to connect the COF force constants to the molecular force constants of the linker molecules and thus enable an efficient description of elastic deformations. To illustrate this aspect, we calculate the deformation energy of different COFs containing the equivalent of a Stone-Wales defect and find very good agreement with the coarse-grained description. © 2022 American Chemical Society. All rights reserved.},
      keywords={Coarse-grained modeling; Deformation; Honeycomb structures, Coarse-grained; Coarse-grained description; Computational approach; Covalent organic frameworks; Density functional-based tight binding methods; Force constants; Performance; Plane elastic properties; Single layer; Two-dimensional, Mechanical stability},
      correspondence_address1={Croy, A.; Institute of Physical Chemistry, Germany; email: alexander.croy@uni-jena.de},
      publisher={American Chemical Society},
      issn={19327447},
      language={English},
      abbrev_source_title={J. Phys. Chem. C},
      document_type={Article},
      source={Scopus},
      }

  • Charge-Compensated N-Doped π-Conjugated Polymers: Toward both Thermodynamic Stability of N-Doped States in Water and High Electron Conductivity
    • F. Borrmann, T. Tsuda, O. Guskova, N. Kiriy, C. Hoffmann, D. Neusser, S. Ludwigs, U. Lappan, F. Simon, M. Geisler, B. Debnath, Y. Krupskaya, M. Al-Hussein, A. Kiriy
    • Advanced Science 9, 2203530 (2022)
    • DOI   Abstract  

      The understanding and applications of electron-conducting π-conjugated polymers with naphtalene diimide (NDI) blocks show remarkable progress in recent years. Such polymers demonstrate a facilitated n-doping due to the strong electron deficiency of the main polymer chain and the presence of the positively charged side groups stabilizing a negative charge of the n-doped backbone. Here, the n-type conducting NDI polymer with enhanced stability of its n-doped states for prospective “in-water” applications is developed. A combined experimental–theoretical approach is used to identify critical features and parameters that control the doping and electron transport process. The facilitated polymer reduction ability and the thermodynamic stability in water are confirmed by electrochemical measurements and doping studies. This material also demonstrates a high conductivity of 10−2 S cm−1 under ambient conditions and 10−1 S cm−1 in vacuum. The modeling explains the stabilizing effects for various dopants. The simulations show a significant doping-induced “collapse” of the positively charged side chains on the core bearing a partial negative charge. This explains a decrease in the lamellar spacing observed in experiments. This study fundamentally enables a novel pathway for achieving both thermodynamic stability of the n-doped states in water and the high electron conductivity of polymers. © 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.

      @ARTICLE{Borrmann2022,
      author={Borrmann, F. and Tsuda, T. and Guskova, O. and Kiriy, N. and Hoffmann, C. and Neusser, D. and Ludwigs, S. and Lappan, U. and Simon, F. and Geisler, M. and Debnath, B. and Krupskaya, Y. and Al-Hussein, M. and Kiriy, A.},
      title={Charge-Compensated N-Doped π-Conjugated Polymers: Toward both Thermodynamic Stability of N-Doped States in Water and High Electron Conductivity},
      journal={Advanced Science},
      year={2022},
      volume={9},
      number={31},
      doi={10.1002/advs.202203530},
      art_number={2203530},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85137350073&doi=10.1002%2fadvs.202203530&partnerID=40&md5=ac2d63e8b755f3b8f25d22620dd7c489},
      affiliation={Leibniz-Institut für Polymerforschung Dresden e.V, Hohe Straße 6, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; IPOC-Functional Polymers, Institute of Polymer Chemistry & Center for Integrated Quantum Science and Technology (IQST), University of Stuttgart, Pfaffenwaldring 55, Stuttgart, 70569, Germany; Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Helmholtzstraße 20, Dresden, 01069, Germany; Physics Department and Hamdi Mango Center for Scientific Research, The University of Jordan, Amman, 11942, Jordan},
      abstract={The understanding and applications of electron-conducting π-conjugated polymers with naphtalene diimide (NDI) blocks show remarkable progress in recent years. Such polymers demonstrate a facilitated n-doping due to the strong electron deficiency of the main polymer chain and the presence of the positively charged side groups stabilizing a negative charge of the n-doped backbone. Here, the n-type conducting NDI polymer with enhanced stability of its n-doped states for prospective “in-water” applications is developed. A combined experimental–theoretical approach is used to identify critical features and parameters that control the doping and electron transport process. The facilitated polymer reduction ability and the thermodynamic stability in water are confirmed by electrochemical measurements and doping studies. This material also demonstrates a high conductivity of 10−2 S cm−1 under ambient conditions and 10−1 S cm−1 in vacuum. The modeling explains the stabilizing effects for various dopants. The simulations show a significant doping-induced “collapse” of the positively charged side chains on the core bearing a partial negative charge. This explains a decrease in the lamellar spacing observed in experiments. This study fundamentally enables a novel pathway for achieving both thermodynamic stability of the n-doped states in water and the high electron conductivity of polymers. © 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.},
      author_keywords={density functional theory calculations; electron conductivity; n-doped states; thermodynamic stability; π-conjugated polymers},
      keywords={Conjugated polymers; Density functional theory; Doping (additives); Electron transport properties, Density-functional theory calculations; Diimide; Doped state; Electron conducting; Electron conductivity; N-doped; N-doped state; Negative charge; Positively charged; π-conjugated polymer, Thermodynamic stability},
      correspondence_address1={Guskova, O.; Leibniz-Institut für Polymerforschung Dresden e.V, Hohe Straße 6, Germany; email: guskova@ipfdd.de; Kiriy, A.; Leibniz-Institut für Polymerforschung Dresden e.V, Hohe Straße 6, Germany; email: ankiriy77@gmail.com},
      publisher={John Wiley and Sons Inc},
      issn={21983844},
      pubmed_id={36065004},
      language={English},
      abbrev_source_title={Adv. Sci.},
      document_type={Article},
      source={Scopus},
      }

  • Spiropyran/Merocyanine Amphiphile in Various Solvents: A Joint Experimental–Theoretical Approach to Photophysical Properties and Self-Assembly
    • V. Savchenko, N. Lomadze, S. Santer, O. Guskova
    • International Journal of Molecular Sciences 23, 11535 (2022)
    • DOI   Abstract  

      This joint experimental-theoretical work focuses on molecular and photophysical properties of the spiropyran-containing amphiphilic molecule in organic and aqueous solutions. Being dissolved in tested organic solvents, the system demonstrates positive photochromism, i.e., upon UV stimulus the colorless spiropyran form is transformed into colorful merocyanine isomer. However, the aqueous solution of the amphiphile possesses a negative photochromism: the orange-red merocyanine form becomes thermodynamically more stable in water, and both UV and vis stimuli lead to the partial or complete photobleaching of the solution. The explanation of this phenomenon is given on the basis of density functional theory calculations and classical modeling including thermodynamic integration. The simulations reveal that stabilization of merocyanine in water proceeds with the energy of ca. 70 kJ mol (Formula presented.), and that the Helmholtz free energy of hydration of merocyanine form is 100 kJ mol (Formula presented.) lower as compared to the behavior of SP isomer in water. The explanation of such a difference lies in the molecular properties of the merocyanine: after ring-opening reaction this molecule transforms into a zwitterionic form, as evidenced by the electrostatic potential plotted around the opened form. The presence of three charged groups on the periphery of a flat conjugated backbone stimulates the self-assembly of merocyanine molecules in water, ending up with the formation of elongated associates with stack-like building blocks, as shown in molecular dynamics simulations of the aqueous solution with the concentration above critical micelle concentration. Our quantitative evaluation of the hydrophilicity switching in spiropyran/merocyanine containing surfactants may prompt the search for new systems, including colloidal and polymeric ones, aiming at remote tuning of their morphology, which could give new promising shapes and patterns for the needs of modern nanotechnology. © 2022 by the authors.

      @ARTICLE{Savchenko2022,
      author={Savchenko, V. and Lomadze, N. and Santer, S. and Guskova, O.},
      title={Spiropyran/Merocyanine Amphiphile in Various Solvents: A Joint Experimental–Theoretical Approach to Photophysical Properties and Self-Assembly},
      journal={International Journal of Molecular Sciences},
      year={2022},
      volume={23},
      number={19},
      doi={10.3390/ijms231911535},
      art_number={11535},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85139952281&doi=10.3390%2fijms231911535&partnerID=40&md5=5a0bf3494d7771704e913e9d9ebfd4bf},
      affiliation={Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Strasse 24-25, Potsdam, 14476, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={This joint experimental-theoretical work focuses on molecular and photophysical properties of the spiropyran-containing amphiphilic molecule in organic and aqueous solutions. Being dissolved in tested organic solvents, the system demonstrates positive photochromism, i.e., upon UV stimulus the colorless spiropyran form is transformed into colorful merocyanine isomer. However, the aqueous solution of the amphiphile possesses a negative photochromism: the orange-red merocyanine form becomes thermodynamically more stable in water, and both UV and vis stimuli lead to the partial or complete photobleaching of the solution. The explanation of this phenomenon is given on the basis of density functional theory calculations and classical modeling including thermodynamic integration. The simulations reveal that stabilization of merocyanine in water proceeds with the energy of ca. 70 kJ mol (Formula presented.), and that the Helmholtz free energy of hydration of merocyanine form is 100 kJ mol (Formula presented.) lower as compared to the behavior of SP isomer in water. The explanation of such a difference lies in the molecular properties of the merocyanine: after ring-opening reaction this molecule transforms into a zwitterionic form, as evidenced by the electrostatic potential plotted around the opened form. The presence of three charged groups on the periphery of a flat conjugated backbone stimulates the self-assembly of merocyanine molecules in water, ending up with the formation of elongated associates with stack-like building blocks, as shown in molecular dynamics simulations of the aqueous solution with the concentration above critical micelle concentration. Our quantitative evaluation of the hydrophilicity switching in spiropyran/merocyanine containing surfactants may prompt the search for new systems, including colloidal and polymeric ones, aiming at remote tuning of their morphology, which could give new promising shapes and patterns for the needs of modern nanotechnology. © 2022 by the authors.},
      author_keywords={molecular modeling; negative photochromism; spiropyran/merocyanine isomerization; time-resolved UV-vis measurements},
      keywords={benzopyran derivative; indole derivative; merocyanine; nitro derivative; solvent; spiropyran; surfactant; water, micelle, Benzopyrans; Indoles; Micelles; Nitro Compounds; Solvents; Surface-Active Agents; Water},
      correspondence_address1={Guskova, O.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: guskova@ipfdd.de},
      publisher={MDPI},
      issn={16616596},
      pubmed_id={36232836},
      language={English},
      abbrev_source_title={Int. J. Mol. Sci.},
      document_type={Article},
      source={Scopus},
      }

  • Explicit temperature coupling in phase-field crystal models of solidification
    • M. Punke, S. M. Wise, A. Voigt, M. Salvalaglio
    • Modelling and Simulation in Materials Science and Engineering 30, 074004 (2022)
    • DOI   Abstract  

      We present a phase-field crystal model for solidification that accounts for thermal transport and a temperature-dependent lattice parameter. Elasticity effects are characterized through the continuous elastic field computed from the microscopic density field. We showcase the model capabilities via selected numerical investigations which focus on the prototypical growth of two-dimensional crystals from the melt, resulting in faceted shapes and dendrites. This work sets the grounds for a comprehensive mesoscale model of solidification including thermal expansion. © 2022 The Author(s). Published by IOP Publishing Ltd.

      @ARTICLE{Punke2022,
      author={Punke, M. and Wise, S.M. and Voigt, A. and Salvalaglio, M.},
      title={Explicit temperature coupling in phase-field crystal models of solidification},
      journal={Modelling and Simulation in Materials Science and Engineering},
      year={2022},
      volume={30},
      number={7},
      doi={10.1088/1361-651X/ac8abd},
      art_number={074004},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85138441863&doi=10.1088%2f1361-651X%2fac8abd&partnerID=40&md5=5faaee1c41749f3b3984ba4707938967},
      affiliation={Institute of Scientific Computing, TU Dresden, Dresden, 01062, Germany; Department of Mathematics, The University of Tennessee, Knoxville, TN 37996, United States; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany},
      abstract={We present a phase-field crystal model for solidification that accounts for thermal transport and a temperature-dependent lattice parameter. Elasticity effects are characterized through the continuous elastic field computed from the microscopic density field. We showcase the model capabilities via selected numerical investigations which focus on the prototypical growth of two-dimensional crystals from the melt, resulting in faceted shapes and dendrites. This work sets the grounds for a comprehensive mesoscale model of solidification including thermal expansion. © 2022 The Author(s). Published by IOP Publishing Ltd.},
      author_keywords={crystal growth; heat flux; phase-field crystal; solidification; thermal expansion},
      keywords={Crystal growth; Heat flux; Thermal expansion, Density fields; Elastic fields; Elasticity effect; In-phase; Numerical investigations; Phase-field crystal models; Phase-field crystals; Temperature dependent; Thermal transport; Two-dimensional crystals, Solidification},
      correspondence_address1={Salvalaglio, M.; Institute of Scientific Computing, Germany; email: marco.salvalaglio@tu-dresden.de},
      publisher={Institute of Physics},
      issn={09650393},
      coden={MSMEE},
      language={English},
      abbrev_source_title={Modell Simul Mater Sci Eng},
      document_type={Article},
      source={Scopus},
      }

  • Structure-property relationships of imperfect additively manufactured lattices based on triply periodic minimal surfaces
    • F. Günther, F. Hirsch, S. Pilz, M. Wagner, A. Gebert, M. Kästner, M. Zimmermann
    • Materials and Design 222, 111036 (2022)
    • DOI   Abstract  

      Lattices based on triply periodic minimal surfaces (TPMS) have recently attracted increasing interest, but their additive manufacturing (AM) is fraught with imperfections that compromise their structural integrity. Initial research has addressed the influence of process-induced imperfections in lattices, but so far numerical work for TPMS lattices is insufficient. Therefore, in the present study, the structure–property relationships of TPMS lattices, including their imperfections, are investigated experimentally and numerically. The main focus is on a biomimetic Schoen I-WP network lattice made of laser powder bed fusion (LPBF) processed Ti-42Nb designed for bone tissue engineering (BTE). The lattice is scanned by computed tomography (CT) and its as-built morphology is examined before a modeling procedure for artificial reconstruction is developed. The structure–property relationships are analyzed by experimental and numerical compression tests. An anisotropic elastoplastic material model is parameterized for finite element analyses (FEA). The numerical results indicates that the reconstruction of the as-built morphology decisively improves the prediction accuracy compared to the ideal design. This work highlights the central importance of process-related imperfections for the structure–property relationships of TPMS lattices and proposes a modeling procedure to capture their implications. © 2022 The Author(s)

      @ARTICLE{Günther2022,
      author={Günther, F. and Hirsch, F. and Pilz, S. and Wagner, M. and Gebert, A. and Kästner, M. and Zimmermann, M.},
      title={Structure-property relationships of imperfect additively manufactured lattices based on triply periodic minimal surfaces},
      journal={Materials and Design},
      year={2022},
      volume={222},
      doi={10.1016/j.matdes.2022.111036},
      art_number={111036},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85135871519&doi=10.1016%2fj.matdes.2022.111036&partnerID=40&md5=33309c660f1097d82a955402b183a5c0},
      affiliation={Institute of Material Science, TU Dresden, Helmholtzstraße 7, Dresden, 01069, Germany; Institute for Material and Beam Technology, Fraunhofer IWS, Winterbergstraße 28, Dresden, 01277, Germany; Institute of Solid Mechanics, TU Dresden, George-Bähr-Straße 3c, Dresden, 01069, Germany; Institute for Complex Material, Leibniz IFW Dresden, Helmholtzstraße 20, Dresden, 01069, Germany; Dresden Center for Fatigue and Reliability, DCFR, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, DCMS, Dresden, 01062, Germany},
      abstract={Lattices based on triply periodic minimal surfaces (TPMS) have recently attracted increasing interest, but their additive manufacturing (AM) is fraught with imperfections that compromise their structural integrity. Initial research has addressed the influence of process-induced imperfections in lattices, but so far numerical work for TPMS lattices is insufficient. Therefore, in the present study, the structure–property relationships of TPMS lattices, including their imperfections, are investigated experimentally and numerically. The main focus is on a biomimetic Schoen I-WP network lattice made of laser powder bed fusion (LPBF) processed Ti-42Nb designed for bone tissue engineering (BTE). The lattice is scanned by computed tomography (CT) and its as-built morphology is examined before a modeling procedure for artificial reconstruction is developed. The structure–property relationships are analyzed by experimental and numerical compression tests. An anisotropic elastoplastic material model is parameterized for finite element analyses (FEA). The numerical results indicates that the reconstruction of the as-built morphology decisively improves the prediction accuracy compared to the ideal design. This work highlights the central importance of process-related imperfections for the structure–property relationships of TPMS lattices and proposes a modeling procedure to capture their implications. © 2022 The Author(s)},
      author_keywords={Additive manufacturing; Defect modeling; Lattice structures; Manufacturing defects; Structure–property relationship; Triply periodic minimal surfaces},
      keywords={3D printers; Additives; Binary alloys; Biomimetics; Compression testing; Computerized tomography; Industrial research; Morphology; Niobium alloys; Structural properties; Tissue engineering; Titanium alloys, Defect model; Laser powders; Lattice structures; Lattice-based; Manufacturing defects; Manufacturing IS; Modeling procedure; Structure-properties relationships; Surface lattice; Triply periodic minimal surfaces, Defects},
      correspondence_address1={Günther, F.; Institute of Material Science, TU Dresden, Helmholtzstraße 7, Germany; email: fabian.guenther@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={02641275},
      language={English},
      abbrev_source_title={Mater. Des.},
      document_type={Article},
      source={Scopus},
      }

  • Phase-field modeling of fatigue crack growth during tooth flank fracture in case-hardened spur gears
    • T. Schneider, D. Müller, M. Seiler, T. Tobie, K. Stahl, M. Kästner
    • International Journal of Fatigue 163, 107091 (2022)
    • DOI   Abstract  

      Tooth flank fracture (TFF) is a fatigue failure mode in gears in which the crack is initiated in a larger depth below the surface within the tooth volume. The crack propagates load-dependently and is not visually observable until final rupture of the tooth. The present publication focuses on numerical fatigue crack simulation of TFF in case-hardened spur gears. Herein, an existing phase-field model for fatigue fracture is revisited and extended to account for the simultaneous subsurface crack initiation and growth in high cycle fatigue during TFF. For this purpose, a gear tooth finite element model is implemented and parameterized using experimental data. Inhomogeneous material properties and residual stresses resulting from the manufacturing process are explicitly considered. The main interest of the study lies in the ability of the phase-field model to reproduce experimentally observable behavior during TFF such as subsurface crack initiation and the emerging subsurface crack path. © 2022

      @ARTICLE{Schneider2022,
      author={Schneider, T. and Müller, D. and Seiler, M. and Tobie, T. and Stahl, K. and Kästner, M.},
      title={Phase-field modeling of fatigue crack growth during tooth flank fracture in case-hardened spur gears},
      journal={International Journal of Fatigue},
      year={2022},
      volume={163},
      doi={10.1016/j.ijfatigue.2022.107091},
      art_number={107091},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85132869913&doi=10.1016%2fj.ijfatigue.2022.107091&partnerID=40&md5=f81988b091c9c4b7832048cf9815f219},
      affiliation={Chair of Computational and Experimental Solid Mechanics, TU Dresden, Dresden, Germany; Gear Research Center (FZG), Technical University of Munich, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, Germany; Dresden Center for Fatigue and Reliability (DCFR), Dresden, Germany},
      abstract={Tooth flank fracture (TFF) is a fatigue failure mode in gears in which the crack is initiated in a larger depth below the surface within the tooth volume. The crack propagates load-dependently and is not visually observable until final rupture of the tooth. The present publication focuses on numerical fatigue crack simulation of TFF in case-hardened spur gears. Herein, an existing phase-field model for fatigue fracture is revisited and extended to account for the simultaneous subsurface crack initiation and growth in high cycle fatigue during TFF. For this purpose, a gear tooth finite element model is implemented and parameterized using experimental data. Inhomogeneous material properties and residual stresses resulting from the manufacturing process are explicitly considered. The main interest of the study lies in the ability of the phase-field model to reproduce experimentally observable behavior during TFF such as subsurface crack initiation and the emerging subsurface crack path. © 2022},
      author_keywords={Gears; High cycle fatigue; Phase-field; Subsurface fatigue; Tooth flank fracture},
      keywords={Fatigue crack propagation; Fracture; Gear teeth; Hardening; High-cycle fatigue; Spur gears, Cracks initiations; Fatigue cracks; Fatigue failure mode; High cycle fatigue; Phase field models; Phase fields; Subsurface cracks; Subsurface fatigue; Tooth flank; Tooth flank fracture, Crack initiation},
      correspondence_address1={Kästner, M.; Chair of Computational and Experimental Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={01421123},
      coden={IJFAD},
      language={English},
      abbrev_source_title={Int J Fatigue},
      document_type={Article},
      source={Scopus},
      }

  • Phase-field modeling of brittle fracture along the thickness direction of plates and shells
    • M. Ambati, J. Heinzmann, M. Seiler, M. Kästner
    • International Journal for Numerical Methods in Engineering 123, 4094-4118 (2022)
    • DOI   Abstract  

      The prediction of fracture in thin-walled structures is decisive for a wide range of applications. Modeling methods such as the phase-field method usually consider cracks to be constant over the thickness which, especially in load cases involving bending, is an imperfect approximation. In this contribution, fracture phenomena along the thickness direction of structural elements (plates or shells) are addressed with a phase-field modeling approach. For this purpose, a new, so called “mixed-dimensional” model is introduced, which combines structural elements representing the displacement field in the two-dimensional shell midsurface with continuum elements describing a crack phase-field in the three-dimensional solid space. The proposed model uses two separate finite element discretizations, where the transfer of variables between the coupled two- and three-dimensional fields is performed at the integration points which in turn need to have corresponding geometric locations. The governing equations of the proposed mixed-dimensional model are deduced in a consistent manner from a total energy functional with them also being compared to existing standard models. The resulting model has the advantage of a reduced computational effort due to the structural elements while still being able to accurately model arbitrary through-thickness crack evolutions as well as partly along the thickness broken shells due to the continuum elements. Amongst others, the higher accuracy as well as the numerical efficiency of the proposed model are tested and validated by comparing simulation results of the new model to those obtained by standard models using numerous representative examples. © 2022 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons Ltd.

      @ARTICLE{Ambati20224094,
      author={Ambati, M. and Heinzmann, J. and Seiler, M. and Kästner, M.},
      title={Phase-field modeling of brittle fracture along the thickness direction of plates and shells},
      journal={International Journal for Numerical Methods in Engineering},
      year={2022},
      volume={123},
      number={17},
      pages={4094-4118},
      doi={10.1002/nme.7001},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85130263295&doi=10.1002%2fnme.7001&partnerID=40&md5=57c08d6d8fdea27cc0dc06edc0af9cc7},
      affiliation={Institute of Solid Mechanics, Technische Universität Dresden, Dresden, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany; Dresden Center for Fatigue and Reliability, Dresden, Germany},
      abstract={The prediction of fracture in thin-walled structures is decisive for a wide range of applications. Modeling methods such as the phase-field method usually consider cracks to be constant over the thickness which, especially in load cases involving bending, is an imperfect approximation. In this contribution, fracture phenomena along the thickness direction of structural elements (plates or shells) are addressed with a phase-field modeling approach. For this purpose, a new, so called “mixed-dimensional” model is introduced, which combines structural elements representing the displacement field in the two-dimensional shell midsurface with continuum elements describing a crack phase-field in the three-dimensional solid space. The proposed model uses two separate finite element discretizations, where the transfer of variables between the coupled two- and three-dimensional fields is performed at the integration points which in turn need to have corresponding geometric locations. The governing equations of the proposed mixed-dimensional model are deduced in a consistent manner from a total energy functional with them also being compared to existing standard models. The resulting model has the advantage of a reduced computational effort due to the structural elements while still being able to accurately model arbitrary through-thickness crack evolutions as well as partly along the thickness broken shells due to the continuum elements. Amongst others, the higher accuracy as well as the numerical efficiency of the proposed model are tested and validated by comparing simulation results of the new model to those obtained by standard models using numerous representative examples. © 2022 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons Ltd.},
      author_keywords={fracture along thickness direction of shells; Kirchhoff–Love shell; mixed-dimensional model; partly through thickness broken shells; phase-field model},
      keywords={Cracks; Phase transitions; Plates (structural components); Shells (structures), Continuum elements; Fracture along thickness direction of shell; Kirchhoff-love shells; Mixed-dimensional models; Partly through thickness broken shell; Phase field models; Standard model; Structural elements; Thickness direction; Through-thickness, Thin walled structures},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={John Wiley and Sons Ltd},
      issn={00295981},
      coden={IJNMB},
      language={English},
      abbrev_source_title={Int. J. Numer. Methods Eng.},
      document_type={Article},
      source={Scopus},
      }

  • Microstructure Characterization and Reconstruction in Python: MCRpy
    • P. Seibert, A. Raßloff, K. Kalina, M. Ambati, M. Kästner
    • Integrating Materials and Manufacturing Innovation 11, 450-466 (2022)
    • DOI   Abstract  

      Microstructure characterization and reconstruction (MCR) is an important prerequisite for empowering and accelerating integrated computational materials engineering. Much progress has been made in MCR recently; however, in the absence of a flexible software platform it is difficult to use ideas from other researchers and to develop them further. To address this issue, this work presents MCRpy as an easy-to-use, extensible and flexible open-source MCR software platform. MCRpy can be used as a program with graphical user interface, as a command line tool and as a Python library. The central idea is that microstructure reconstruction is formulated as a modular and extensible optimization problem. In this way, arbitrary descriptors can be used for characterization and arbitrary loss functions combining arbitrary descriptors can be minimized using arbitrary optimizers for reconstructing random heterogeneous media. With stochastic optimizers, this leads to variations of the well-known Yeong–Torquato algorithm. Furthermore, MCRpy features automatic differentiation, enabling the utilization of gradient-based optimizers. In this work, after a brief introduction to the underlying concepts, the capabilities of MCRpy are demonstrated by exemplarily applying it to typical MCR tasks. Finally, it is shown how to extend MCRpy by defining a new microstructure descriptor and readily using it for reconstruction without additional implementation effort. © 2022, The Author(s).

      @ARTICLE{Seibert2022450,
      author={Seibert, P. and Raßloff, A. and Kalina, K. and Ambati, M. and Kästner, M.},
      title={Microstructure Characterization and Reconstruction in Python: MCRpy},
      journal={Integrating Materials and Manufacturing Innovation},
      year={2022},
      volume={11},
      number={3},
      pages={450-466},
      doi={10.1007/s40192-022-00273-4},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85138026719&doi=10.1007%2fs40192-022-00273-4&partnerID=40&md5=61fad519d5d1e3c7a1d89318ca0ffc2d},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Dresden Center for Fatigue and Reliability, TU Dresden, Dresden, 01062, Germany},
      abstract={Microstructure characterization and reconstruction (MCR) is an important prerequisite for empowering and accelerating integrated computational materials engineering. Much progress has been made in MCR recently; however, in the absence of a flexible software platform it is difficult to use ideas from other researchers and to develop them further. To address this issue, this work presents MCRpy as an easy-to-use, extensible and flexible open-source MCR software platform. MCRpy can be used as a program with graphical user interface, as a command line tool and as a Python library. The central idea is that microstructure reconstruction is formulated as a modular and extensible optimization problem. In this way, arbitrary descriptors can be used for characterization and arbitrary loss functions combining arbitrary descriptors can be minimized using arbitrary optimizers for reconstructing random heterogeneous media. With stochastic optimizers, this leads to variations of the well-known Yeong–Torquato algorithm. Furthermore, MCRpy features automatic differentiation, enabling the utilization of gradient-based optimizers. In this work, after a brief introduction to the underlying concepts, the capabilities of MCRpy are demonstrated by exemplarily applying it to typical MCR tasks. Finally, it is shown how to extend MCRpy by defining a new microstructure descriptor and readily using it for reconstruction without additional implementation effort. © 2022, The Author(s).},
      author_keywords={Characterization; Descriptor; ICME; Microstructure; Reconstruction; Software},
      keywords={Graphical user interfaces; Microstructure; Open source software; Open systems; Optimization; Stochastic systems, Characterization; Computational materials; Descriptors; ICME; Microstructure characterization; Microstructure reconstruction; Optimizers; Reconstruction; Software; Software platforms, Python},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Springer Science and Business Media Deutschland GmbH},
      issn={21939764},
      language={English},
      abbrev_source_title={Integr. Mat. Manuf. Innov.},
      document_type={Article},
      source={Scopus},
      }

  • Influence of CT image processing on the predicted impact of pores on fatigue of additively manufactured Ti6Al4V and AlSi10Mg
    • U. Gebhardt, P. Schulz, A. Raßloff, I. Koch, M. Gude, M. Kästner
    • GAMM Mitteilungen 45, e202200017 (2022)
    • DOI   Abstract  

      Pores are inherent to additively manufactured components and critical especially in technical components. Since they reduce the component’s fatigue life, a reliable identification and description of pores is vital to ensure the component’s performance. X-ray computed tomography (CT) is an established and non-destructive testing method to investigate internal defects. The CT scan process can induce noise and artefacts in the resulting images which afterwards have to be reduced through image processing. To reconstruct the internal defects of a component, the images need to be segmented in defect region and bulk material by applying a threshold. The application of the threshold as well as the previous image processing alter the geometry and size of the identified defects. This contribution aims to quantify the influence of selected commercial image processing and segmentation methods on identified pores in several additively manufactured components made of AlSi10Mg and Ti6Al4V as well as in an artificial CT scan. To that aim, gray value histograms and characteristic parameters thereof are compared for different image processing tools. After the segmentation of the processed images, particle characteristics are compared. The influence of image processing and segmentation on the predicted fatigue life of the material is evaluated through the change of the largest pore in each set of data applying Murakami’s empirical (Formula presented.) -parameter model. © 2022 The Authors. GAMM – Mitteilungen published by Wiley-VCH GmbH.

      @ARTICLE{Gebhardt2022,
      author={Gebhardt, U. and Schulz, P. and Raßloff, A. and Koch, I. and Gude, M. and Kästner, M.},
      title={Influence of CT image processing on the predicted impact of pores on fatigue of additively manufactured Ti6Al4V and AlSi10Mg},
      journal={GAMM Mitteilungen},
      year={2022},
      volume={45},
      number={3-4},
      doi={10.1002/gamm.202200017},
      art_number={e202200017},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85133667158&doi=10.1002%2fgamm.202200017&partnerID=40&md5=beb17662fb9dbb6620d5faa12e1c0407},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, Germany; Institute of Lightweight Engineering and Polymer Technology, TU Dresden, Dresden, Germany; Dresden Center for Fatigue and Reliability, TU Dresden, Dresden, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, Germany},
      abstract={Pores are inherent to additively manufactured components and critical especially in technical components. Since they reduce the component's fatigue life, a reliable identification and description of pores is vital to ensure the component's performance. X-ray computed tomography (CT) is an established and non-destructive testing method to investigate internal defects. The CT scan process can induce noise and artefacts in the resulting images which afterwards have to be reduced through image processing. To reconstruct the internal defects of a component, the images need to be segmented in defect region and bulk material by applying a threshold. The application of the threshold as well as the previous image processing alter the geometry and size of the identified defects. This contribution aims to quantify the influence of selected commercial image processing and segmentation methods on identified pores in several additively manufactured components made of AlSi10Mg and Ti6Al4V as well as in an artificial CT scan. To that aim, gray value histograms and characteristic parameters thereof are compared for different image processing tools. After the segmentation of the processed images, particle characteristics are compared. The influence of image processing and segmentation on the predicted fatigue life of the material is evaluated through the change of the largest pore in each set of data applying Murakami's empirical (Formula presented.) -parameter model. © 2022 The Authors. GAMM - Mitteilungen published by Wiley-VCH GmbH.},
      author_keywords={additive manufacturing; computed tomography; image processing; pore analysis},
      keywords={3D printers; Additives; Computerized tomography; Defects; Fatigue of materials; Image segmentation; Magnesium alloys; Nondestructive examination; Silicon alloys; Ternary alloys; Titanium alloys, Component performance; Computed tomography; Computed tomography images; Computed tomography scan; Images processing; Images segmentations; Internal defects; Nondestructive testing method; Pore analysis; X-ray computed tomography, Aluminum alloys},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: Markus.Kaestner@tu-dresden.de},
      publisher={John Wiley and Sons Inc},
      issn={09367195},
      language={English},
      abbrev_source_title={GAMM Mitteilungen},
      document_type={Article},
      source={Scopus},
      }

  • A phase field crystal theory of the kinematics of dislocation lines
    • V. Skogvoll, L. Angheluta, A. Skaugen, M. Salvalaglio, J. Viñals
    • Journal of the Mechanics and Physics of Solids 166, 104932 (2022)
    • DOI   Abstract  

      We introduce a dislocation density tensor and derive its kinematic evolution law from a phase field description of crystal deformations in three dimensions. The phase field crystal (PFC) model is used to define the lattice distortion, including topological singularities, and the associated configurational stresses. We derive an exact expression for the velocity of dislocation line determined by the phase field evolution, and show that dislocation motion in the PFC is driven by a Peach–Koehler force. As is well known from earlier PFC model studies, the configurational stress is not divergence free for a general field configuration. Therefore, we also present a method (PFCMEq) to constrain the diffusive dynamics to mechanical equilibrium by adding an independent and integrable distortion so that the total resulting stress is divergence free. In the PFCMEq model, the far-field stress agrees very well with the predictions from continuum elasticity, while the near-field stress around the dislocation core is regularized by the smooth nature of the phase-field. We apply this framework to study the rate of shrinkage of an dislocation loop seeded in its glide plane. © 2022 The Author(s)

      @ARTICLE{Skogvoll2022,
      author={Skogvoll, V. and Angheluta, L. and Skaugen, A. and Salvalaglio, M. and Viñals, J.},
      title={A phase field crystal theory of the kinematics of dislocation lines},
      journal={Journal of the Mechanics and Physics of Solids},
      year={2022},
      volume={166},
      doi={10.1016/j.jmps.2022.104932},
      art_number={104932},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85132432881&doi=10.1016%2fj.jmps.2022.104932&partnerID=40&md5=fc932330d10443a3a7b9c285e5f1815f},
      affiliation={PoreLab, Njord Centre, Department of Physics, University of Oslo, P.O. Box 1048, Oslo, 0316, Norway; Institute of Scientific Computing, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, United States},
      abstract={We introduce a dislocation density tensor and derive its kinematic evolution law from a phase field description of crystal deformations in three dimensions. The phase field crystal (PFC) model is used to define the lattice distortion, including topological singularities, and the associated configurational stresses. We derive an exact expression for the velocity of dislocation line determined by the phase field evolution, and show that dislocation motion in the PFC is driven by a Peach–Koehler force. As is well known from earlier PFC model studies, the configurational stress is not divergence free for a general field configuration. Therefore, we also present a method (PFCMEq) to constrain the diffusive dynamics to mechanical equilibrium by adding an independent and integrable distortion so that the total resulting stress is divergence free. In the PFCMEq model, the far-field stress agrees very well with the predictions from continuum elasticity, while the near-field stress around the dislocation core is regularized by the smooth nature of the phase-field. We apply this framework to study the rate of shrinkage of an dislocation loop seeded in its glide plane. © 2022 The Author(s)},
      author_keywords={Atomistic models; Computational methods; Crystal plasticity; Dislocation dynamics; Phase-field crystal modeling; Structure of solids and liquids},
      keywords={Computation theory; Computational methods; Crystal structure; Dislocations (crystals); Kinematics; Topology, Atomistic modelling; Crystal plasticity; Dislocation density tensors; Dislocation dynamics; Dislocation lines; Divergence free; Phase fields; Phase-field crystal models; Phase-field crystals; Structure of solid and liquid, Stresses},
      correspondence_address1={Skogvoll, V.; PoreLab, P.O. Box 1048, Norway; email: vidarsko@uio.no},
      publisher={Elsevier Ltd},
      issn={00225096},
      coden={JMPSA},
      language={English},
      abbrev_source_title={J Mech Phys Solids},
      document_type={Article},
      source={Scopus},
      }

  • Ground-state properties of p-type delafossite transparent conducting oxides 2H-CuMO2 (M=Al, Sc and Y): DFT calculations
    • M. Hadjab, O. Guskova, H. Bennacer, M. I. Ziane, A. H. Larbi, M. A. Saeed
    • Materials Today Communications 32, 103995 (2022)
    • DOI   Abstract  

      In this study, we have investigated physical ground-state properties of three novel semiconductors to address many problems related to the photovoltaic (PV) industry. A computational package (wien2k) based on Density Functional Theory (DFT) is used to study the optical, structural, as well as electronic properties of delafossite transparent conducting oxides CuMO2 (M= Al, Sc and Y). The Full-Potential Linearized Augmented Plan Wave method (FP-LAPW) which is based on DFT has also been employed in this study. To compute the structural and electronic parameters the Local Density Approximation (LDA), Perdew, Burke and Ernzerhof Generalized Gradient Approximation (PBE-GGA) have been utilized as the exchange-correlation term. Furthermore, Tran-Blaha modified Beck–Johnson potential (TB-mBJ) has been utilized to achieve better degree of accuracy in computing the electronic and optical characteristics. The results of the study have also been compared to the previous theoretical and experimental ones. The ternary delafossite transparent conducting oxide compounds can be considered as an alternative material in photovoltaic applications. © 2022 Elsevier Ltd

      @ARTICLE{Hadjab2022,
      author={Hadjab, M. and Guskova, O. and Bennacer, H. and Ziane, M.I. and Larbi, A.H. and Saeed, M.A.},
      title={Ground-state properties of p-type delafossite transparent conducting oxides 2H-CuMO2 (M=Al, Sc and Y): DFT calculations},
      journal={Materials Today Communications},
      year={2022},
      volume={32},
      doi={10.1016/j.mtcomm.2022.103995},
      art_number={103995},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85134629781&doi=10.1016%2fj.mtcomm.2022.103995&partnerID=40&md5=f85c1720b34dc1c362bb3eb3c7f11fcd},
      affiliation={Electronics Department, Faculty of Technology, Mohamed Boudiaf University of M'sila, M'sila, 28000, Algeria; Leibniz Institute of Polymer Research Dresden Institute of Theory of Polymers, Dresden, 01069, Germany; Technische Universität Dresden, Dresden Center for Computational Materials Science (DCMS), Dresden, 01062, Germany; École Supérieur en Génie Électrique et Énergétique d'Oran (ESGEE), Oran, 31000, Algeria; Research Center in Industrial Technologies CRTI, P.O. Box 64, Cheraga, Algiers 16014, Algeria; Department of Physics, Division of Science & Technology, University of Education, Lahore, Pakistan},
      abstract={In this study, we have investigated physical ground-state properties of three novel semiconductors to address many problems related to the photovoltaic (PV) industry. A computational package (wien2k) based on Density Functional Theory (DFT) is used to study the optical, structural, as well as electronic properties of delafossite transparent conducting oxides CuMO2 (M= Al, Sc and Y). The Full-Potential Linearized Augmented Plan Wave method (FP-LAPW) which is based on DFT has also been employed in this study. To compute the structural and electronic parameters the Local Density Approximation (LDA), Perdew, Burke and Ernzerhof Generalized Gradient Approximation (PBE-GGA) have been utilized as the exchange-correlation term. Furthermore, Tran-Blaha modified Beck–Johnson potential (TB-mBJ) has been utilized to achieve better degree of accuracy in computing the electronic and optical characteristics. The results of the study have also been compared to the previous theoretical and experimental ones. The ternary delafossite transparent conducting oxide compounds can be considered as an alternative material in photovoltaic applications. © 2022 Elsevier Ltd},
      author_keywords={CuMO2; Delafossite transparent conducting oxides; First-principles calculations; FP-LAPW; Optoelectronic properties; Structural parameters},
      keywords={Calculations; Computation theory; Electronic properties; Ground state; Local density approximation; Scandium, CuMO2; Delafossite transparent conducting oxide; Delafossites; First principle calculations; Full-potential linearized augmented plan wave method; Optoelectronics property; Plan wave; Structural parameter; Transparent conducting oxide; Wave method, Transparent conducting oxides},
      correspondence_address1={Hadjab, M.; Electronics Department, Algeria; email: moufdi.hadjab@univ-msila.dz},
      publisher={Elsevier Ltd},
      issn={23524928},
      language={English},
      abbrev_source_title={Mater. Today Commun.},
      document_type={Article},
      source={Scopus},
      }

  • Additively manufactured AlSi10Mg lattices – Potential and limits of modelling as-designed structures
    • U. Gebhardt, T. Gustmann, L. Giebeler, F. Hirsch, J. K. Hufenbach, M. Kästner
    • Materials and Design 220, 110796 (2022)
    • DOI   Abstract  

      Additive manufacturing overcomes the restrictions of classical manufacturing methods and enables the production of near-net-shaped, complex geometries. In that context, lattice structures are of high interest due to their superior weight reduction potential. AlSi10Mg is a well-known alloy for additive manufacturing and well suited for such applications due to its high strength to material density ratio. It has been selected in this study for producing bulk material and complex geometries of a strut-based lattice type (rhombic dodecahedron). A detailed characterisation of as-built and heat-treated specimens has been conducted including microstructural analyses, identification of imperfections and rigorous mechanical testing under different load conditions. An isotropic elastic–plastic material model is deduced on the basis of tension test results of bulk material test specimens. Performed experiments under compression, shear, torsion and tension load are compared to their virtual equivalents. With the help of numerical modelling, the overall structural behaviour was simulated using the detailed lattice geometry and was successfully predicted by the presented numerical models. The discussion of the limits of this approach aims to evaluate the potential of the numerical assessment in the modelling of the properties for novel lightweight structures. © 2022 The Authors

      @ARTICLE{Gebhardt2022,
      author={Gebhardt, U. and Gustmann, T. and Giebeler, L. and Hirsch, F. and Hufenbach, J.K. and Kästner, M.},
      title={Additively manufactured AlSi10Mg lattices – Potential and limits of modelling as-designed structures},
      journal={Materials and Design},
      year={2022},
      volume={220},
      doi={10.1016/j.matdes.2022.110796},
      art_number={110796},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85132345209&doi=10.1016%2fj.matdes.2022.110796&partnerID=40&md5=16e959a173d148d316503eda298fcea0},
      affiliation={Chair of Computational and Experimental Solid Mechanics, Institute of Solid Mechanics, TU Dresden, Dresden, 01062, Germany; Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research Dresden, Dresden, 01069, Germany; Institute of Materials Science, Technische Universität Bergakademie Freiberg, Gustav-Zeuner-Str. 5, Freiberg, 09599, Germany; Dresden Center for Computational Materials Science (DCMS), Dresden, Germany},
      abstract={Additive manufacturing overcomes the restrictions of classical manufacturing methods and enables the production of near-net-shaped, complex geometries. In that context, lattice structures are of high interest due to their superior weight reduction potential. AlSi10Mg is a well-known alloy for additive manufacturing and well suited for such applications due to its high strength to material density ratio. It has been selected in this study for producing bulk material and complex geometries of a strut-based lattice type (rhombic dodecahedron). A detailed characterisation of as-built and heat-treated specimens has been conducted including microstructural analyses, identification of imperfections and rigorous mechanical testing under different load conditions. An isotropic elastic–plastic material model is deduced on the basis of tension test results of bulk material test specimens. Performed experiments under compression, shear, torsion and tension load are compared to their virtual equivalents. With the help of numerical modelling, the overall structural behaviour was simulated using the detailed lattice geometry and was successfully predicted by the presented numerical models. The discussion of the limits of this approach aims to evaluate the potential of the numerical assessment in the modelling of the properties for novel lightweight structures. © 2022 The Authors},
      author_keywords={Additive manufacturing; Al-based alloy; Elastic–plastic material model; Experimental characterisation; Lattice structures; Material characterisation},
      keywords={Additives; Aluminum alloys; Geometry; High strength alloys; Materials handling equipment; Numerical models; Tensile testing, Al-based alloys; Bulk materials; Complex geometries; Elastic-plastic Material; Elastic–plastic material model; Experimental characterization; Lattice potentials; Lattice structures; Material modeling; Materials characterization, 3D printers},
      correspondence_address1={Kästner, M.; Chair of Computational and Experimental Solid Mechanics, TU Dresden, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={02641275},
      language={English},
      abbrev_source_title={Mater. Des.},
      document_type={Article},
      source={Scopus},
      }

  • Multiple low-energy excitons and optical response of d0 double perovskite Ba2ScTaO6
    • A. K. Himanshu, S. Kumar, U. Dey, R. Ray
    • Physica B: Condensed Matter 637, 413856 (2022)
    • DOI   Abstract  

      Large bandgap insulators are considered promising for applications such as photocatalysts, dielectric resonators and interference filters. Based on synchrotron X-ray diffraction, diffuse reflectance measurement and density functional theory, we report the crystal structure, optical response, and electronic properties of the synthesized d0 double perovskite Ba2ScTaO6. In contrast to earlier prediction, the electronic bandgap is found to be large, ∼4.66eV. The optical response is characterized by the presence of multiple exciton modes extending up to the visible range. A detailed investigation of the direct gap excitons based on the Elliot formula is presented. Density functional theory based investigation of the electronic properties within generalized gradient approximation severely underestimates the electronic gap. To reach a quantitative agreement, we consider different available flavors of the modified-Becke–Johnson exchange–correlation potential and discuss their effects on the electronic and optical properties. © 2022 Elsevier B.V.

      @ARTICLE{Himanshu2022,
      author={Himanshu, A.K. and Kumar, S. and Dey, U. and Ray, R.},
      title={Multiple low-energy excitons and optical response of d0 double perovskite Ba2ScTaO6},
      journal={Physica B: Condensed Matter},
      year={2022},
      volume={637},
      doi={10.1016/j.physb.2022.413856},
      art_number={413856},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85128182716&doi=10.1016%2fj.physb.2022.413856&partnerID=40&md5=baa483e00584e89e6785a6edf8447215},
      affiliation={Variable Energy Cyclotron Center (VECC), DAE, 1/AF Bidhannagar, Kolkata, 700064, India; Homi Bhabha National Institute, Mumbai, 400094, India; Department of Physics, Magadh University, Bodh Gaya, 824234, India; Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India; Department of Physics, Durham University, South Road, Durham, DH1 3LE, United Kingdom; Institute for Theoretical Solid State Physics, Leibniz IFW Dresden, Helmholtzstr. 20, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Department of Physics, Birla Institute of Technology Mesra, Jharkhand, Ranchi, 835215, India},
      abstract={Large bandgap insulators are considered promising for applications such as photocatalysts, dielectric resonators and interference filters. Based on synchrotron X-ray diffraction, diffuse reflectance measurement and density functional theory, we report the crystal structure, optical response, and electronic properties of the synthesized d0 double perovskite Ba2ScTaO6. In contrast to earlier prediction, the electronic bandgap is found to be large, ∼4.66eV. The optical response is characterized by the presence of multiple exciton modes extending up to the visible range. A detailed investigation of the direct gap excitons based on the Elliot formula is presented. Density functional theory based investigation of the electronic properties within generalized gradient approximation severely underestimates the electronic gap. To reach a quantitative agreement, we consider different available flavors of the modified-Becke–Johnson exchange–correlation potential and discuss their effects on the electronic and optical properties. © 2022 Elsevier B.V.},
      author_keywords={DFT; Double Perovskites; Excitons; mBJ; SXRD; UV–Vis spectroscopy},
      keywords={Crystal structure; Density functional theory; Dielectric devices; Electronic properties; Energy gap; Excitons; Optical correlation; Optical properties, Density-functional-theory; DFT; Dielectric interference filters; Dielectric resonator filters; Double perovskites; Lower energies; MBJ; Optical response; SXRD; UV/ Vis spectroscopy, Perovskite},
      correspondence_address1={Himanshu, A.K.; Institute for Theoretical Solid State Physics, Helmholtzstr. 20, Germany; email: akhimanshu@gmail.com},
      publisher={Elsevier B.V.},
      issn={09214526},
      coden={PHYBE},
      language={English},
      abbrev_source_title={Phys B Condens Matter},
      document_type={Article},
      source={Scopus},
      }

  • Extended high-harmonic spectra through a cascade resonance in confined quantum systems
    • X. Zhang, T. Zhu, H. Du, H. -G. Luo, J. Van Den Brink, R. Ray
    • Physical Review Research 4, 033026 (2022)
    • DOI   Abstract  

      The study of high-harmonic generation in confined quantum systems is vital to establishing a complete physical picture of harmonic generation from atoms and molecules to bulk solids. Based on a multilevel approach, we demonstrate how intraband resonances significantly influence the harmonic spectra via charge pumping to the higher subbands and thus redefine the cutoff laws. As a proof of principle, we consider the interaction of graphene nanoribbons, with zigzag as well as armchair terminations, and resonant fields polarized along the cross-ribbon direction. Here, this effect is particularly prominent due to many nearly equiseparated energy levels. In such a scenario, a cascade resonance effect can take place in high-harmonic generation when the field strength is above a critical threshold, which is completely different from the harmonic generation mechanism of atoms, molecules, and bulk solids. We further discuss the implications not only for other systems in a nanoribbon geometry, but also systems where only a few subbands (energy levels) meet this frequency-matching condition by considering a generalized multilevel Hamiltonian. Our study highlights that cascade resonance has a fundamentally distinct influence on the laws of harmonic generation, specifically the cutoff laws based on laser duration, field strength, and wavelength, thus unraveling additional insights in solid-state high-harmonic generation. © 2022 authors. Published by the American Physical Society.

      @ARTICLE{Zhang2022,
      author={Zhang, X. and Zhu, T. and Du, H. and Luo, H.-G. and Van Den Brink, J. and Ray, R.},
      title={Extended high-harmonic spectra through a cascade resonance in confined quantum systems},
      journal={Physical Review Research},
      year={2022},
      volume={4},
      number={3},
      doi={10.1103/PhysRevResearch.4.033026},
      art_number={033026},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85135951200&doi=10.1103%2fPhysRevResearch.4.033026&partnerID=40&md5=57d729a2a0dffad52a31e624395b2c3a},
      affiliation={Institute for Theoretical Solid State Physics, Leibniz IFW Dresden, Helmholtzstrasse 20, Dresden, 01069, Germany; School of Physical Science and Technology, Lanzhou Center of Theoretical Physics, Lanzhou University, Lanzhou, 730000, China; School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; Beijing Computational Science Research Center, Beijing, 100084, China; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Institute of Theoretical Physics and Würzburg-Dresden Cluster of Excellence Ct.qmat, Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={The study of high-harmonic generation in confined quantum systems is vital to establishing a complete physical picture of harmonic generation from atoms and molecules to bulk solids. Based on a multilevel approach, we demonstrate how intraband resonances significantly influence the harmonic spectra via charge pumping to the higher subbands and thus redefine the cutoff laws. As a proof of principle, we consider the interaction of graphene nanoribbons, with zigzag as well as armchair terminations, and resonant fields polarized along the cross-ribbon direction. Here, this effect is particularly prominent due to many nearly equiseparated energy levels. In such a scenario, a cascade resonance effect can take place in high-harmonic generation when the field strength is above a critical threshold, which is completely different from the harmonic generation mechanism of atoms, molecules, and bulk solids. We further discuss the implications not only for other systems in a nanoribbon geometry, but also systems where only a few subbands (energy levels) meet this frequency-matching condition by considering a generalized multilevel Hamiltonian. Our study highlights that cascade resonance has a fundamentally distinct influence on the laws of harmonic generation, specifically the cutoff laws based on laser duration, field strength, and wavelength, thus unraveling additional insights in solid-state high-harmonic generation. © 2022 authors. Published by the American Physical Society.},
      keywords={Chemical industry; Cutoff frequency; Graphene; Hamiltonians; Harmonic analysis; Harmonic generation; Molecules; Nanoribbons; Quantum optics, Bulk-solids; Charge pumping; Confined quantum systems; Field strengths; Harmonics generation; High harmonic generation; High-harmonic spectrum; Multilevel approach; Physical pictures, Resonance},
      publisher={American Physical Society},
      issn={26431564},
      language={English},
      abbrev_source_title={Phys. Rev. Res.},
      document_type={Article},
      source={Scopus},
      }

  • Coarse-grained modeling of crystals by the amplitude expansion of the phase-field crystal model: An overview
    • M. Salvalaglio, K. R. Elder
    • Modelling and Simulation in Materials Science and Engineering 30, 053001 (2022)
    • DOI   Abstract  

      Comprehensive investigations of crystalline systems often require methods bridging atomistic and continuum scales. In this context, coarse-grained mesoscale approaches are of particular interest as they allow the examination of large systems and time scales while retaining some microscopic details. The so-called phase-field crystal (PFC) model conveniently describes crystals at diffusive time scales through a continuous periodic field which varies on atomic scales and is related to the atomic number density. To go beyond the restrictive atomic length scales of the PFC model, a complex amplitude formulation was first developed by Goldenfeld et al (2005 Phys. Rev. E 72 020601). While focusing on length scales larger than the lattice parameter, this approach can describe crystalline defects, interfaces, and lattice deformations. It has been used to examine many phenomena including liquid/solid fronts, grain boundary energies, and strained films. This topical review focuses on this amplitude expansion of the PFC model and its developments. An overview of the derivation, connection to the continuum limit, representative applications, and extensions is presented. A few practical aspects, such as suitable numerical methods and examples, are illustrated as well. Finally, the capabilities and bounds of the model, current challenges, and future perspectives are addressed. © 2022 The Author(s). Published by IOP Publishing Ltd.

      @ARTICLE{Salvalaglio2022,
      author={Salvalaglio, M. and Elder, K.R.},
      title={Coarse-grained modeling of crystals by the amplitude expansion of the phase-field crystal model: An overview},
      journal={Modelling and Simulation in Materials Science and Engineering},
      year={2022},
      volume={30},
      number={5},
      doi={10.1088/1361-651X/ac681e},
      art_number={053001},
      note={cited By 5},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85131398300&doi=10.1088%2f1361-651X%2fac681e&partnerID=40&md5=fca36f0681b05122918050e6e4d91b10},
      affiliation={Institute of Scientific Computing, TU-Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU-Dresden, Dresden, 01062, Germany; Department of Physics, Oakland University, Rochester, MI 48309, United States},
      abstract={Comprehensive investigations of crystalline systems often require methods bridging atomistic and continuum scales. In this context, coarse-grained mesoscale approaches are of particular interest as they allow the examination of large systems and time scales while retaining some microscopic details. The so-called phase-field crystal (PFC) model conveniently describes crystals at diffusive time scales through a continuous periodic field which varies on atomic scales and is related to the atomic number density. To go beyond the restrictive atomic length scales of the PFC model, a complex amplitude formulation was first developed by Goldenfeld et al (2005 Phys. Rev. E 72 020601). While focusing on length scales larger than the lattice parameter, this approach can describe crystalline defects, interfaces, and lattice deformations. It has been used to examine many phenomena including liquid/solid fronts, grain boundary energies, and strained films. This topical review focuses on this amplitude expansion of the PFC model and its developments. An overview of the derivation, connection to the continuum limit, representative applications, and extensions is presented. A few practical aspects, such as suitable numerical methods and examples, are illustrated as well. Finally, the capabilities and bounds of the model, current challenges, and future perspectives are addressed. © 2022 The Author(s). Published by IOP Publishing Ltd.},
      author_keywords={amplitude expansion; crystal defects; crystal growth; crystals; elasticity; phase-field-crystal models; plasticity},
      keywords={Atoms; Crystal growth; Grain boundaries; Numerical methods, Amplitude expansion; Atomistics; Coarse-grained; Coarse-grained modeling; Crystalline systems; Large system; Meso scale; Periodic fields; Phase-field crystal models; Time-scales, Crystals},
      correspondence_address1={Salvalaglio, M.; Institute of Scientific Computing, Germany; email: marco.salvalaglio@tu-dresden.de},
      publisher={Institute of Physics},
      issn={09650393},
      coden={MSMEE},
      language={English},
      abbrev_source_title={Modell Simul Mater Sci Eng},
      document_type={Review},
      source={Scopus},
      }

  • The contribution of intermolecular spin interactions to the London dispersion forces between chiral molecules
    • M. Geyer, R. Gutierrez, V. Mujica, J. F. R. Silva, A. Dianat, G. Cuniberti
    • Journal of Chemical Physics 156, 234106 (2022)
    • DOI   Abstract  

      Dispersion interactions are one of the components of van der Waals (vdW) forces that play a key role in the understanding of intermolecular interactions in many physical, chemical, and biological processes. The theory of dispersion forces was developed by London in the early years of quantum mechanics. However, it was only in the 1960s that it was recognized that for molecules lacking an inversion center, such as chiral and helical molecules, there are chirality-sensitive corrections to the dispersion forces proportional to the rotatory power known from the theory of circular dichroism and with the same distance scaling law R-6 as the London energy. The discovery of the chirality-induced spin selectivity effect in recent years has led to an additional twist in the study of chiral molecular systems, showing a close relation between spin and molecular geometry. Motivated by it, we propose in this investigation to describe the mutual induction of charge and spin-density fluctuations in a pair A-B of chiral molecules by a simple physical model. The model assumes that the same fluctuating electric fields responsible for vdW forces can induce a magnetic response via a Rashba-like term so that a spin-orbit field acting on molecule B is generated by the electric field arising from charge density fluctuations in molecule A (and vice versa). Within a second-order perturbative approach, these contributions manifest as an effective intermolecular exchange interaction. Although expected to be weaker than the standard London forces, these interactions display the same R-6 distance scaling. © 2022 Author(s).

      @ARTICLE{Geyer2022,
      author={Geyer, M. and Gutierrez, R. and Mujica, V. and Silva, J.F.R. and Dianat, A. and Cuniberti, G.},
      title={The contribution of intermolecular spin interactions to the London dispersion forces between chiral molecules},
      journal={Journal of Chemical Physics},
      year={2022},
      volume={156},
      number={23},
      doi={10.1063/5.0090266},
      art_number={234106},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85132289023&doi=10.1063%2f5.0090266&partnerID=40&md5=3f0fee30f79286db6c70b923eca2ee06},
      affiliation={Institute For Materials Science And Max Bergmann Center Of Biomaterials, Dresden University Of Technology, Dresden, 01062, Germany; Arizona State University, School Of Molecular Sciences, P.O. Box 871604, Tempe, AZ 85287-1604, United States; Kimika Fakultatea, Euskal Herriko Unibertsitatea And Donostia International Physics Center (DIPC), P. K. 1072, Euskadi, Donostia, 20080, Spain; Instituto De Física Luis Rivera Terrazas, Benemérita Universidad Autónoma De Puebla, Apdo. Postal J48, Col. San Manuel Puebla Pue.C. P. 72570, Mexico; Dresden Center For Computational Materials Science, Center For Advancing Electronics Dresden, Tu Dresden, Dresden, 01062, Germany},
      abstract={Dispersion interactions are one of the components of van der Waals (vdW) forces that play a key role in the understanding of intermolecular interactions in many physical, chemical, and biological processes. The theory of dispersion forces was developed by London in the early years of quantum mechanics. However, it was only in the 1960s that it was recognized that for molecules lacking an inversion center, such as chiral and helical molecules, there are chirality-sensitive corrections to the dispersion forces proportional to the rotatory power known from the theory of circular dichroism and with the same distance scaling law R-6 as the London energy. The discovery of the chirality-induced spin selectivity effect in recent years has led to an additional twist in the study of chiral molecular systems, showing a close relation between spin and molecular geometry. Motivated by it, we propose in this investigation to describe the mutual induction of charge and spin-density fluctuations in a pair A-B of chiral molecules by a simple physical model. The model assumes that the same fluctuating electric fields responsible for vdW forces can induce a magnetic response via a Rashba-like term so that a spin-orbit field acting on molecule B is generated by the electric field arising from charge density fluctuations in molecule A (and vice versa). Within a second-order perturbative approach, these contributions manifest as an effective intermolecular exchange interaction. Although expected to be weaker than the standard London forces, these interactions display the same R-6 distance scaling. © 2022 Author(s).},
      keywords={Chirality; Dichroism; Dispersions; Electric fields; Molecules; Quantum theory; Spin fluctuations; Stereochemistry, Charge density fluctuations; Chemical and biologicals; Chiral molecule; Dispersion force; Dispersion interaction; Intermolecular interactions; London dispersion forces; Physical-chemical process; Spin interaction; Van der waals' forces, Van der Waals forces, England; quantum theory; stereoisomerism, London; Quantum Theory; Stereoisomerism},
      correspondence_address1={Gutierrez, R.; Institute For Materials Science And Max Bergmann Center Of Biomaterials, Germany; email: rafael.gutierrez@tu-dresden.de},
      publisher={American Institute of Physics Inc.},
      issn={00219606},
      coden={JCPSA},
      pubmed_id={35732515},
      language={English},
      abbrev_source_title={J Chem Phys},
      document_type={Article},
      source={Scopus},
      }

  • Emerging Internet of Things driven carbon nanotubes-based devices
    • S. Zhang, J. Pang, Y. Li, F. Yang, T. Gemming, K. Wang, X. Wang, S. Peng, X. Liu, B. Chang, H. Liu, W. Zhou, G. Cuniberti, M. H. Rümmeli
    • Nano Research 15, 4613-4637 (2022)
    • DOI   Abstract  

      Carbon nanotubes (CNTs) have attracted great attentions in the field of electronics, sensors, healthcare, and energy conversion. Such emerging applications have driven the carbon nanotube research in a rapid fashion. Indeed, the structure control over CNTs has inspired an intensive research vortex due to the high promises in electronic and optical device applications. Here, this in-depth review is anticipated to provide insights into the controllable synthesis and applications of high-quality CNTs. First, the general synthesis and post-purification of CNTs are briefly discussed. Then, the state-of-the-art electronic device applications are discussed, including field-effect transistors, gas sensors, DNA biosensors, and pressure gauges. Besides, the optical sensors are delivered based on the photoluminescence. In addition, energy applications of CNTs are discussed such as thermoelectric energy generators. Eventually, future opportunities are proposed for the Internet of Things (IoT) oriented sensors, data processing, and artificial intelligence. [Figure not available: see fulltext.] © 2021, The Author(s).

      @ARTICLE{Zhang20224613,
      author={Zhang, S. and Pang, J. and Li, Y. and Yang, F. and Gemming, T. and Wang, K. and Wang, X. and Peng, S. and Liu, X. and Chang, B. and Liu, H. and Zhou, W. and Cuniberti, G. and Rümmeli, M.H.},
      title={Emerging Internet of Things driven carbon nanotubes-based devices},
      journal={Nano Research},
      year={2022},
      volume={15},
      number={5},
      pages={4613-4637},
      doi={10.1007/s12274-021-3986-7},
      note={cited By 12},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85123060011&doi=10.1007%2fs12274-021-3986-7&partnerID=40&md5=3d7ed1f47d96d9a0e208253875b2f1c8},
      affiliation={Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Jinan, 250022, China; Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen, 518055, China; Leibniz Institute for Solid State and Materials Research Dresden, P.O. Box 270116, Dresden, D-01171, Germany; State Key Laboratory of Crystal Materials, Center of Bio & Micro/Nano Functional Materials, Shandong University, 27 Shandanan Road, Jinan, 250100, China; School of Electrical Engineering, Qingdao University, Qingdao, 266071, China; Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Avenue, Shenzhen University Town, Shenzhen, 518055, China; High-Frequency High-Voltage Device and Integrated Circuits R&D Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China; Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China; School of Chemistry and Chemical Engineering, University of Jinan, Jinan, 250022, China; College of Energy, Soochow Institute for Energy and Materials Innovations, Soochow University, Suzhou, 215006, China; Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie Sklodowskiej 34, Zabrze, 41-819, Poland; Institute of Environmental Technology (CEET), VŠB-Technical University of Ostrava, 17. Listopadu 15, Ostrava, 708 33, Czech Republic; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Intelligent Materials (GCL DCIM), Technische Universität Dresden, Dresden, 01062, Germany; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01069, Germany},
      abstract={Carbon nanotubes (CNTs) have attracted great attentions in the field of electronics, sensors, healthcare, and energy conversion. Such emerging applications have driven the carbon nanotube research in a rapid fashion. Indeed, the structure control over CNTs has inspired an intensive research vortex due to the high promises in electronic and optical device applications. Here, this in-depth review is anticipated to provide insights into the controllable synthesis and applications of high-quality CNTs. First, the general synthesis and post-purification of CNTs are briefly discussed. Then, the state-of-the-art electronic device applications are discussed, including field-effect transistors, gas sensors, DNA biosensors, and pressure gauges. Besides, the optical sensors are delivered based on the photoluminescence. In addition, energy applications of CNTs are discussed such as thermoelectric energy generators. Eventually, future opportunities are proposed for the Internet of Things (IoT) oriented sensors, data processing, and artificial intelligence. [Figure not available: see fulltext.] © 2021, The Author(s).},
      author_keywords={artificial intelligence; carbon nanotubes; electronic skins; electronics; Internet of Things; sensors},
      keywords={Artificial intelligence; Data handling; Energy conversion; Field effect transistors; Internet of things, Device application; Electronic energies; Electronic healthcare; Electronic sensors; Electronic skin; Emerging applications; Nanotube research; Nanotube-based devices; Sensor; Structure control, Carbon nanotubes},
      correspondence_address1={Pang, J.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, China; email: jinbo.pang@hotmail.com; Liu, H.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, China; email: hongliu@sdu.edu.cn; Yang, F.; Department of Chemistry, China; email: yangf3@sustech.edu.cn; Cuniberti, G.; Dresden Center for Computational Materials Science, Germany; email: gianaurelio.cuniberti@tu-dresden.de},
      publisher={Tsinghua University},
      issn={19980124},
      language={English},
      abbrev_source_title={Nano. Res.},
      document_type={Review},
      source={Scopus},
      }

  • An effective formaldehyde gas sensor based on oxygen-rich three-dimensional graphene
    • S. Zhang, J. Pang, Y. Li, B. Ibarlucea, Y. Liu, T. Wang, X. Liu, S. Peng, T. Gemming, Q. Cheng, H. Liu, J. Yang, G. Cuniberti, W. Zhou, M. H. Rümmeli
    • Nanotechnology 33, 185702 (2022)
    • DOI   Abstract  

      Three-dimensional (3D) graphene with a high specific surface area and excellent electrical conductivity holds extraordinary potential for molecular gas sensing. Gas molecules adsorbed onto graphene serve as electron donors, leading to an increase in conductivity. However, several challenges remain for 3D graphene-based gas sensors, such as slow response and long recovery time. Therefore, research interest remains in the promotion of the sensitivity of molecular gas detection. In this study, we fabricate oxygen plasma-treated 3D graphene for the high-performance gas sensing of formaldehyde. We synthesize large-area, high-quality, 3D graphene over Ni foam by chemical vapor deposition and obtain freestanding 3D graphene foam after Ni etching. We compare three types of strategies – non-treatment, oxygen plasma, and etching in HNO3 solution – for the posttreatment of 3D graphene. Eventually, the strategy for oxygen plasma-treated 3D graphene exceeds expectations, which may highlight the general gas sensing based on chemiresistors. © 2022 The Author(s). Published by IOP Publishing Ltd.

      @ARTICLE{Zhang2022,
      author={Zhang, S. and Pang, J. and Li, Y. and Ibarlucea, B. and Liu, Y. and Wang, T. and Liu, X. and Peng, S. and Gemming, T. and Cheng, Q. and Liu, H. and Yang, J. and Cuniberti, G. and Zhou, W. and Rümmeli, M.H.},
      title={An effective formaldehyde gas sensor based on oxygen-rich three-dimensional graphene},
      journal={Nanotechnology},
      year={2022},
      volume={33},
      number={18},
      doi={10.1088/1361-6528/ac4eb4},
      art_number={185702},
      note={cited By 5},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85124498878&doi=10.1088%2f1361-6528%2fac4eb4&partnerID=40&md5=6e1ce08251570cf12ff629fbc52f39a0},
      affiliation={Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy, Universities of Shandong, Institute for Advanced Interdisciplinary Research (IAIR), University of Jinan, Shandong, Jinan, 250022, China; School of Chemistry and Chemical Engineering, University of Jinan, Shandong, Jinan, 250022, China; Institute for Materials Science, Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, D-01069, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, D-01069, Germany; College of Energy, Soochow Institute for Energy and Materials Innovations, Soochow University, Suzhou, 215006, China; Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China; State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, No.3501 Daxue Road, Jinan, 250353, China; School of Bioengineering, Qilu University of Technology, Shandong Academy of Science, Jinan, 250353, China; High-Frequency High-Voltage Device and Integrated Circuits RandD Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China; Key Laboratory of Microelectronic Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China; Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research Dresden, PO Box 270116, Dresden, D-01171, Germany; State Key Laboratory of Crystal Materials, Center of Bio and Micro/Nano Functional Materials, Shandong University, 27 Shandanan Road, Jinan, 250100, China; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, D-01062, Germany; Dresden Center for Intelligent Materials (GCL DCIM), Technische Universität Dresden, Dresden D-01062, Germany; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie Sklodowskiej 34, Zabrze, 41-819, Poland; Institute of Environmental Technology (CEET), VŠB-Technical University of Ostrava, 17. Listopadu 15, Ostrava, 708 33, Czech Republic},
      abstract={Three-dimensional (3D) graphene with a high specific surface area and excellent electrical conductivity holds extraordinary potential for molecular gas sensing. Gas molecules adsorbed onto graphene serve as electron donors, leading to an increase in conductivity. However, several challenges remain for 3D graphene-based gas sensors, such as slow response and long recovery time. Therefore, research interest remains in the promotion of the sensitivity of molecular gas detection. In this study, we fabricate oxygen plasma-treated 3D graphene for the high-performance gas sensing of formaldehyde. We synthesize large-area, high-quality, 3D graphene over Ni foam by chemical vapor deposition and obtain freestanding 3D graphene foam after Ni etching. We compare three types of strategies - non-treatment, oxygen plasma, and etching in HNO3 solution - for the posttreatment of 3D graphene. Eventually, the strategy for oxygen plasma-treated 3D graphene exceeds expectations, which may highlight the general gas sensing based on chemiresistors. © 2022 The Author(s). Published by IOP Publishing Ltd.},
      author_keywords={3D graphene; chemical vapor deposition; chemiresistors; gas sensing; oxygen plasma treatments},
      keywords={Chemical detection; Chemical sensors; Chemical vapor deposition; Etching; Formaldehyde; Graphene; Molecules; Nickel; Oxygen, 3D graphene; Chemical vapour deposition; Chemiresistors; Gas sensing; Gas-sensors; High specific surface area; Molecular gas; Oxygen plasma treatments; Oxygen plasmas; Three-dimensional graphene, Gas detectors},
      correspondence_address1={Pang, J.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy, Shandong, China; email: ifc_pangjb@ujn.edu.cn; Liu, H.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy, Shandong, China; email: hongliu@sdu.edu.cn; Cuniberti, G.; Institute for Materials Science, Germany; email: gianaurelio.cuniberti@tu-dresden.de; Rümmeli, M.H.; College of Energy, China; email: m.ruemmeli@ifw-dresden.de},
      publisher={IOP Publishing Ltd},
      issn={09574484},
      coden={NNOTE},
      pubmed_id={35078155},
      language={English},
      abbrev_source_title={Nanotechnology},
      document_type={Article},
      source={Scopus},
      }

  • Exploring the similarity of single-layer covalent organic frameworks using electronic structure calculations
    • A. Raptakis, A. Croy, A. Dianat, R. Gutierrez, G. Cuniberti
    • RSC Advances 12, 12283-12291 (2022)
    • DOI   Abstract  

      Two-dimensional Covalent Organic Frameworks (2D COFs) have attracted considerable interest because of their potential for a broad range of applications. Different combinations of the monomeric units can lead to potentially novel materials with varying physico-chemical properties. In this study, we investigate the electronic properties of various 2D COFs with square lattice topology based on a tight-binding density functional theory approach. We first classify the 2D COFs into different classes according to the degree of π-conjugation. Interestingly, this classification is recovered by using a similarity measure based on specific features of the electronic band-structure of the COFs. Further, we study the effect of aromaticity on the electronic structure of fully-conjugated COFs. Our results show that the conjugation and aromaticity are keys in the electronic band-structure of COFs. © 2022 The Royal Society of Chemistry

      @ARTICLE{Raptakis202212283,
      author={Raptakis, A. and Croy, A. and Dianat, A. and Gutierrez, R. and Cuniberti, G.},
      title={Exploring the similarity of single-layer covalent organic frameworks using electronic structure calculations},
      journal={RSC Advances},
      year={2022},
      volume={12},
      number={20},
      pages={12283-12291},
      doi={10.1039/d2ra01007k},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85129890799&doi=10.1039%2fd2ra01007k&partnerID=40&md5=10a2a5f76827fd32a926c27d59b810b0},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany; Institute of Physical Chemistry, Friedrich Schiller University Jena, Jena, 07737, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Two-dimensional Covalent Organic Frameworks (2D COFs) have attracted considerable interest because of their potential for a broad range of applications. Different combinations of the monomeric units can lead to potentially novel materials with varying physico-chemical properties. In this study, we investigate the electronic properties of various 2D COFs with square lattice topology based on a tight-binding density functional theory approach. We first classify the 2D COFs into different classes according to the degree of π-conjugation. Interestingly, this classification is recovered by using a similarity measure based on specific features of the electronic band-structure of the COFs. Further, we study the effect of aromaticity on the electronic structure of fully-conjugated COFs. Our results show that the conjugation and aromaticity are keys in the electronic band-structure of COFs. © 2022 The Royal Society of Chemistry},
      keywords={Band structure; Density functional theory; Electronic structure; Lattice theory, Aromaticities; Covalent organic frameworks; Electronic band structure; Electronic structure calculations; Monomeric units; Novel materials; Physicochemical property; Single layer; Square lattices; Two-dimensional, Electronic properties},
      correspondence_address1={Gutierrez, R.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: rafael.gutierrez@tu-dresden.de},
      publisher={Royal Society of Chemistry},
      issn={20462069},
      coden={RSCAC},
      language={English},
      abbrev_source_title={RSC Adv.},
      document_type={Article},
      source={Scopus},
      }

  • Descriptor-based reconstruction of three-dimensional microstructures through gradient-based optimization
    • P. Seibert, A. Raßloff, M. Ambati, M. Kästner
    • Acta Materialia 227, 117667 (2022)
    • DOI   Abstract  

      Microstructure reconstruction is an important cornerstone to the inverse materials design concept. In this work, a general algorithm is developed to reconstruct a three-dimensional microstructure from given descriptors. Based on two-dimensional (2D) micrographs, this reconstruction algorithm allows valuable insight through spatial visualization of the microstructure and in silico studies of structure-property linkages. The formulation ensures computational efficiency by casting microstructure reconstruction as a gradient-based optimization problem. Herein, the descriptors can be chosen freely, such as spatial correlations or Gram matrices, as long as they are differentiable with respect to the microstructure. Because real microstructure samples are commonly available as 2D microscopy images only, the desired descriptors for the reconstruction process are prescribed on orthogonal 2D slices. This adds a source of noise, which is handled in a new, superior and interpretable manner. The efficiency and applicability of this formulation is demonstrated by various numerical experiments. © 2022

      @ARTICLE{Seibert2022,
      author={Seibert, P. and Raßloff, A. and Ambati, M. and Kästner, M.},
      title={Descriptor-based reconstruction of three-dimensional microstructures through gradient-based optimization},
      journal={Acta Materialia},
      year={2022},
      volume={227},
      doi={10.1016/j.actamat.2022.117667},
      art_number={117667},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85123711935&doi=10.1016%2fj.actamat.2022.117667&partnerID=40&md5=32a19a88e61363753a4516f852a80905},
      affiliation={Institute of Solid Mechanics, Technische Universität Dresden, Dresden, 01069, Germany; George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, Georgia; Dresden Center for Computational Materials Science, TU Dresden, Dresden, Germany; Dresden Center for Fatigue and Reliability, TU Dresden, Dresden, Germany},
      abstract={Microstructure reconstruction is an important cornerstone to the inverse materials design concept. In this work, a general algorithm is developed to reconstruct a three-dimensional microstructure from given descriptors. Based on two-dimensional (2D) micrographs, this reconstruction algorithm allows valuable insight through spatial visualization of the microstructure and in silico studies of structure-property linkages. The formulation ensures computational efficiency by casting microstructure reconstruction as a gradient-based optimization problem. Herein, the descriptors can be chosen freely, such as spatial correlations or Gram matrices, as long as they are differentiable with respect to the microstructure. Because real microstructure samples are commonly available as 2D microscopy images only, the desired descriptors for the reconstruction process are prescribed on orthogonal 2D slices. This adds a source of noise, which is handled in a new, superior and interpretable manner. The efficiency and applicability of this formulation is demonstrated by various numerical experiments. © 2022},
      author_keywords={3D Characterization; Gradient-based optimization; Microstructure; Reconstruction; Statistics},
      keywords={Computational efficiency; Efficiency; Image reconstruction; Inverse problems, 3D characterization; Descriptors; Design concept; Gradient-based optimization; Materials design; Microstructure reconstruction; Reconstruction; Reconstruction algorithms; Three-dimensional microstructures; Two-dimensional, Microstructure},
      correspondence_address1={Kästner, M.email: Markus.Kaestner@TU-Dresden.de},
      publisher={Acta Materialia Inc},
      issn={13596454},
      language={English},
      abbrev_source_title={Acta Mater},
      document_type={Article},
      source={Scopus},
      }

  • Bi12Rh3Cu2I5: A 3D Weak Topological Insulator with Monolayer Spacers and Independent Transport Channels
    • E. Carrillo-Aravena, K. Finzel, R. Ray, M. Richter, T. Heider, I. Cojocariu, D. Baranowski, V. Feyer, L. Plucinski, M. Gruschwitz, C. Tegenkamp, M. Ruck
    • Physica Status Solidi (B) Basic Research 259, 2100447 (2022)
    • DOI   Abstract  

      {Topological insulators (TIs) are semiconductors with protected electronic surface states that allow dissipation-free transport. TIs are envisioned as ideal materials for spintronics and quantum computing. In Bi14Rh3I9, the first weak 3D TI, topology presumably arises from stacking of the intermetallic [(Bi4Rh)3I]2+ layers, which are predicted to be 2D TIs and to possess protected edge-states, separated by topologically trivial [Bi2I8]2− octahedra chains. In the new layered salt Bi12Rh3Cu2I5, the same intermetallic layers are separated by planar, i.e., only one atom thick, [Cu2I4]2− anions. Density functional theory (DFT)-based calculations show that the compound is a weak 3D TI, characterized by (Formula presented.), and that the topological gap is generated by strong spin–orbit coupling (E g,calc. ∼ 10 meV). According to a bonding analysis, the copper cations prevent strong coupling between the TI layers. The calculated surface spectral function for a finite-slab geometry shows distinct characteristics for the two terminations of the main crystal faces ⟨001⟩, viz., [(Bi4Rh)3I]2+ and [Cu2I4]2−. Photoelectron spectroscopy data confirm the calculated band structure. In situ four-point probe measurements indicate a highly anisotropic bulk semiconductor (E g

      @ARTICLE{Carrillo-Aravena2022,
      author={Carrillo-Aravena, E. and Finzel, K. and Ray, R. and Richter, M. and Heider, T. and Cojocariu, I. and Baranowski, D. and Feyer, V. and Plucinski, L. and Gruschwitz, M. and Tegenkamp, C. and Ruck, M.},
      title={Bi12Rh3Cu2I5: A 3D Weak Topological Insulator with Monolayer Spacers and Independent Transport Channels},
      journal={Physica Status Solidi (B) Basic Research},
      year={2022},
      volume={259},
      number={4},
      doi={10.1002/pssb.202100447},
      art_number={2100447},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85123505640&doi=10.1002%2fpssb.202100447&partnerID=40&md5=baee7ae40c96fd2788f80d070a640307},
      affiliation={Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden, 01062, Germany; Würzburg–Dresden Cluster of Excellence ct.qmat, c/o Technische Universität Dresden, Dresden, 01062, Germany; Leibniz IFW Dresden, Helmholtzstr. 20, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Peter Grünberg Institute PGI-6, Forschungszentrum Jülich, Jülich, 52425, Germany; Institute of Physics, Technische Universität Chemnitz, Reichenhainer Str. 70, Chemnitz, 09126, Germany; Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, Dresden, 01187, Germany},
      abstract={Topological insulators (TIs) are semiconductors with protected electronic surface states that allow dissipation-free transport. TIs are envisioned as ideal materials for spintronics and quantum computing. In Bi14Rh3I9, the first weak 3D TI, topology presumably arises from stacking of the intermetallic [(Bi4Rh)3I]2+ layers, which are predicted to be 2D TIs and to possess protected edge-states, separated by topologically trivial [Bi2I8]2− octahedra chains. In the new layered salt Bi12Rh3Cu2I5, the same intermetallic layers are separated by planar, i.e., only one atom thick, [Cu2I4]2− anions. Density functional theory (DFT)-based calculations show that the compound is a weak 3D TI, characterized by (Formula presented.), and that the topological gap is generated by strong spin–orbit coupling (E g,calc. ∼ 10 meV). According to a bonding analysis, the copper cations prevent strong coupling between the TI layers. The calculated surface spectral function for a finite-slab geometry shows distinct characteristics for the two terminations of the main crystal faces ⟨001⟩, viz., [(Bi4Rh)3I]2+ and [Cu2I4]2−. Photoelectron spectroscopy data confirm the calculated band structure. In situ four-point probe measurements indicate a highly anisotropic bulk semiconductor (E g,exp. = 28 meV) with path-independent metallic conductivity restricted to the surface as well as temperature-independent conductivity below 60 K. © 2022 The Authors. physica status solidi (b) basic solid state physics published by Wiley-VCH GmbH.},
      author_keywords={crystal structures; electronic structures; electronic transport; layered compounds; spin–orbit coupling; subvalent compounds; topological insulators},
      keywords={Chemical bonds; Computation theory; Density functional theory; Electric insulators; Intermetallics; Monolayers; Photoelectron spectroscopy; Quantum computers; Topological insulators, 2 layer; Density-functional-theory; Edge state; Electronic surface state; Intermetallic layer; Quantum Computing; Solid-state physics; Stackings; Topological insulators; Transport channel, Topology},
      correspondence_address1={Ruck, M.; Faculty of Chemistry and Food Chemistry, Germany; email: michael.ruck@tu-dresden.de},
      publisher={John Wiley and Sons Inc},
      issn={03701972},
      language={English},
      abbrev_source_title={Phys. Status Solidi B Basic Res.},
      document_type={Article},
      source={Scopus},
      }

  • Disconnection-Mediated migration of interfaces in microstructures: II. diffuse interface simulations
    • M. Salvalaglio, D. J. Srolovitz, J. Han
    • Acta Materialia 227, 117463 (2022)
    • DOI   Abstract  

      The motion of interfaces is an essential feature of microstructure evolution in crystalline materials. While atomic-scale descriptions provide mechanistic clarity, continuum descriptions are important for understanding microstructural evolution and upon which microscopic features it depends. We develop a microstructure evolution simulation approach that is linked to the underlying microscopic mechanisms of interface migration. We extend the continuum approach describing the disconnection-mediated motion of interfaces introduced in Part I [Han, Srolovitz and Salvalaglio, 2021] to a diffuse interface, phase-field model suitable for large-scale microstructure evolution. A broad range of numerical simulations showcases the capability of the method and the influence of microscopic interface migration mechanisms on microstructure evolution. These include, in particular, the effects of stress and its coupling to interface migration which arises from disconnections, showing how this leads to important differences from classical microstructure evolution represented by mean curvature flow. © 2021 Acta Materialia Inc.

      @ARTICLE{Salvalaglio2022,
      author={Salvalaglio, M. and Srolovitz, D.J. and Han, J.},
      title={Disconnection-Mediated migration of interfaces in microstructures: II. diffuse interface simulations},
      journal={Acta Materialia},
      year={2022},
      volume={227},
      doi={10.1016/j.actamat.2021.117463},
      art_number={117463},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85121366745&doi=10.1016%2fj.actamat.2021.117463&partnerID=40&md5=caecf380084948761a5503e2b7c3f2d3},
      affiliation={Institute of Scientific Computing, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Hong Kong Institute for Advanced Study, City University of Hong Kong, Hong Kong SAR, Hong Kong; Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, Hong Kong; Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong SAR, Hong Kong},
      abstract={The motion of interfaces is an essential feature of microstructure evolution in crystalline materials. While atomic-scale descriptions provide mechanistic clarity, continuum descriptions are important for understanding microstructural evolution and upon which microscopic features it depends. We develop a microstructure evolution simulation approach that is linked to the underlying microscopic mechanisms of interface migration. We extend the continuum approach describing the disconnection-mediated motion of interfaces introduced in Part I [Han, Srolovitz and Salvalaglio, 2021] to a diffuse interface, phase-field model suitable for large-scale microstructure evolution. A broad range of numerical simulations showcases the capability of the method and the influence of microscopic interface migration mechanisms on microstructure evolution. These include, in particular, the effects of stress and its coupling to interface migration which arises from disconnections, showing how this leads to important differences from classical microstructure evolution represented by mean curvature flow. © 2021 Acta Materialia Inc.},
      author_keywords={Disconnections; Grain boundaries; Interfaces; Microstructure; Phase field modeling},
      keywords={Microstructure; Numerical methods; Phase interfaces, Atomic-scale description; Continuum description; Diffuse interface; Disconnection; Essential features; Grain-boundaries; Interface migration; Mechanistics; Microstructure evolutions; Phase field models, Grain boundaries},
      correspondence_address1={Salvalaglio, M.; Institute of Scientific Computing, TU Dresden, Germany; email: marco.salvalaglio@tu-dresden.de},
      publisher={Acta Materialia Inc},
      issn={13596454},
      language={English},
      abbrev_source_title={Acta Mater},
      document_type={Article},
      source={Scopus},
      }

  • Disconnection-mediated migration of interfaces in microstructures: I. continuum model
    • J. Han, D. J. Srolovitz, M. Salvalaglio
    • Acta Materialia 227, 117178 (2022)
    • DOI   Abstract  

      A long-standing goal of materials science is to understand, predict and control the evolution of microstructures in crystalline materials. Most microstructure evolution is controlled by interface motion; hence, the establishment of rigorous interface equations of motion is a universal goal of materials science. We present a new model for the motion of arbitrarily curved interfaces that respects the underlying crystallography of the two phases/domains meeting at the interface and is consistent with microscopic mechanisms of interface motion; i.e., disconnection migration (line defects in the interface with step and dislocation character). We derive the equation of motion for interface migration under the influence of a wide range of driving forces. In Part II of this paper [Salvalaglio, Han and Srolovitz, 2021], we implement the interface model and the equation of motion proposed in this paper in a diffuse interface simulation approach for complex morphology and microstructure evolution. © 2021 Acta Materialia Inc.

      @ARTICLE{Han2022,
      author={Han, J. and Srolovitz, D.J. and Salvalaglio, M.},
      title={Disconnection-mediated migration of interfaces in microstructures: I. continuum model},
      journal={Acta Materialia},
      year={2022},
      volume={227},
      doi={10.1016/j.actamat.2021.117178},
      art_number={117178},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85112837362&doi=10.1016%2fj.actamat.2021.117178&partnerID=40&md5=e042ac0dc93283a4b0bef2b01f6d2805},
      affiliation={Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong SAR, Hong Kong; Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, Hong Kong; Hong Kong Institute for Advanced Study, City University of Hong Kong, Hong Kong SAR, Hong Kong; Institute of Scientific Computing, Dresden, TU Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Dresden, TU Dresden, 01062, Germany},
      abstract={A long-standing goal of materials science is to understand, predict and control the evolution of microstructures in crystalline materials. Most microstructure evolution is controlled by interface motion; hence, the establishment of rigorous interface equations of motion is a universal goal of materials science. We present a new model for the motion of arbitrarily curved interfaces that respects the underlying crystallography of the two phases/domains meeting at the interface and is consistent with microscopic mechanisms of interface motion; i.e., disconnection migration (line defects in the interface with step and dislocation character). We derive the equation of motion for interface migration under the influence of a wide range of driving forces. In Part II of this paper [Salvalaglio, Han and Srolovitz, 2021], we implement the interface model and the equation of motion proposed in this paper in a diffuse interface simulation approach for complex morphology and microstructure evolution. © 2021 Acta Materialia Inc.},
      author_keywords={Continuum modeling; Disconnections; Grain boundaries; Interfaces; Microstructure},
      keywords={Continuum mechanics; Crystallites; Microstructural evolution; Morphology; Nanocrystalline materials, Complex morphology; Continuum Modeling; Dislocation characters; Interface equations; Interface migration; Micro-structure evolutions; Microscopic mechanisms; Simulation approach, Equations of motion},
      correspondence_address1={Salvalaglio, M.; Hong Kong Institute for Advanced Study, Hong Kong; email: marco.salvalaglio@tu-dresden.de},
      publisher={Acta Materialia Inc},
      issn={13596454},
      language={English},
      abbrev_source_title={Acta Mater},
      document_type={Article},
      source={Scopus},
      }

  • Observer-invariant time derivatives on moving surfaces
    • I. Nitschke, A. Voigt
    • Journal of Geometry and Physics 173, 104428 (2022)
    • DOI   Abstract  

      Observer-invariance is regarded as a minimum requirement for an appropriate definition of time derivatives. We derive various time derivatives systematically from a spacetime setting, where observer-invariance is a special case of a covariance principle and covered by Ricci-calculus. The analysis is considered for tangential n-tensor fields on moving surfaces and provides formulations which are applicable for numerical computations. For various special cases, e. g., vector fields (n=1) and symmetric and trace-less tensor fields (n=2) we compare material and convected derivatives and demonstrate the different underlying physics. © 2021 Elsevier B.V.

      @ARTICLE{Nitschke2022,
      author={Nitschke, I. and Voigt, A.},
      title={Observer-invariant time derivatives on moving surfaces},
      journal={Journal of Geometry and Physics},
      year={2022},
      volume={173},
      doi={10.1016/j.geomphys.2021.104428},
      art_number={104428},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85121269818&doi=10.1016%2fj.geomphys.2021.104428&partnerID=40&md5=6bfa903b8568419fa4c539606d2e54ac},
      affiliation={Institut für Wissenschaftliches Rechnen, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Center for Systems Biology Dresden (CSBD), Pfotenhauerstr. 108, Dresden, 01307, Germany},
      abstract={Observer-invariance is regarded as a minimum requirement for an appropriate definition of time derivatives. We derive various time derivatives systematically from a spacetime setting, where observer-invariance is a special case of a covariance principle and covered by Ricci-calculus. The analysis is considered for tangential n-tensor fields on moving surfaces and provides formulations which are applicable for numerical computations. For various special cases, e. g., vector fields (n=1) and symmetric and trace-less tensor fields (n=2) we compare material and convected derivatives and demonstrate the different underlying physics. © 2021 Elsevier B.V.},
      author_keywords={Moving surface; Observer-invariance; Spacetime; Tangential tensor fields; Time derivative},
      correspondence_address1={Nitschke, I.; Institut für Wissenschaftliches Rechnen, Germany; email: ingo.nitschke@tu-dresden.de},
      publisher={Elsevier B.V.},
      issn={03930440},
      coden={JGPHE},
      language={English},
      abbrev_source_title={J. Geom. Phys.},
      document_type={Article},
      source={Scopus},
      }

  • A wafer-scale two-dimensional platinum monosulfide ultrathin film: Via metal sulfurization for high performance photoelectronics
    • J. Pang, Y. Wang, X. Yang, L. Zhang, Y. Li, Y. Zhang, J. Yang, F. Yang, X. Wang, G. Cuniberti, H. Liu, M. H. Rümmeli
    • Materials Advances 3, 1497-1505 (2022)
    • DOI   Abstract  

      2D nonlayered materials have attracted enormous research interests due to their novel physical and chemical properties with confined dimensions. Platinum monosulfide as one of the most common platinum-group minerals has been less studied due to either the low purity in the natural product or the extremely high-pressure conditions for synthesis. Recently, platinum monosulfide (PtS) 2D membranes have emerged as rising-star materials for fundamental Raman and X-ray photoelectron spectral analysis as well as device exploration. However, a large-area homogeneous synthesis route has not yet been proposed and released. In this communication, we report a facile metal sulfurization strategy for the synthesis of a 4-inch wafer-scale PtS film. Enhanced characterization tools have been employed for thorough analysis of the crystal structure, chemical environment, vibrational modes, and atomic configuration. Furthermore, through theoretical calculations the phase diagram of the Pt-S compound has been plotted for showing the successful formation of PtS in our synthesis conditions. Eventually, a high-quality PtS film has been reflected in device demonstration by a photodetector. Our approach may shed light on the mass production of PtS films with precise control of their thickness and homogeneity as well as van der Waals heterostructures and related electronic devices. This journal is © The Royal Society of Chemistry.

      @ARTICLE{Pang20221497,
      author={Pang, J. and Wang, Y. and Yang, X. and Zhang, L. and Li, Y. and Zhang, Y. and Yang, J. and Yang, F. and Wang, X. and Cuniberti, G. and Liu, H. and Rümmeli, M.H.},
      title={A wafer-scale two-dimensional platinum monosulfide ultrathin film: Via metal sulfurization for high performance photoelectronics},
      journal={Materials Advances},
      year={2022},
      volume={3},
      number={3},
      pages={1497-1505},
      doi={10.1039/d1ma00757b},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85124625758&doi=10.1039%2fd1ma00757b&partnerID=40&md5=5b00e160370e911e720669d8d0515ea1},
      affiliation={Collab. Innov. Ctr. of Technol. and Equip. for Biol. Diagn. and Therapy in Universities of Shandong, Institute for Advanced Interdisciplinary Research (IAIR), University of Jinan, Shandong, Jinan, 250022, China; Institute of Marine Science and Technology, Shandong University, Shandong, Qingdao, 266237, China; The Interdisciplinary Research Center, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Zhangjiang Hi-Tech Park, 99 Haike Road, Pudong, Shanghai, 201210, China; School of Microelectronics, University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, China; Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China; Department of Chemistry, Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, Shenzhen, 518055, China; Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01069, Germany; State Key Laboratory of Crystal Materials, Center of Bio and Micro/Nano Functional Materials, Shandong University, 27 Shandanan Road, Jinan, 250100, China; College of Energy, Soochow Institute for Energy and Materials Innovations, Soochow University, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie Sklodowskiej 34, Zabrze, 41-819, Poland; Institute for Complex Materials, IFW Dresden, 20 Helmholtz Strasse, Dresden, 01069, Germany; Institute of Environmental Technology, VŠB-Technical University of Ostrava, 17. listopadu 15, Ostrava, 708 33, Czech Republic; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; The Dresden Center for Intelligent Materials (DCIM), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={2D nonlayered materials have attracted enormous research interests due to their novel physical and chemical properties with confined dimensions. Platinum monosulfide as one of the most common platinum-group minerals has been less studied due to either the low purity in the natural product or the extremely high-pressure conditions for synthesis. Recently, platinum monosulfide (PtS) 2D membranes have emerged as rising-star materials for fundamental Raman and X-ray photoelectron spectral analysis as well as device exploration. However, a large-area homogeneous synthesis route has not yet been proposed and released. In this communication, we report a facile metal sulfurization strategy for the synthesis of a 4-inch wafer-scale PtS film. Enhanced characterization tools have been employed for thorough analysis of the crystal structure, chemical environment, vibrational modes, and atomic configuration. Furthermore, through theoretical calculations the phase diagram of the Pt-S compound has been plotted for showing the successful formation of PtS in our synthesis conditions. Eventually, a high-quality PtS film has been reflected in device demonstration by a photodetector. Our approach may shed light on the mass production of PtS films with precise control of their thickness and homogeneity as well as van der Waals heterostructures and related electronic devices. This journal is © The Royal Society of Chemistry.},
      correspondence_address1={Pang, J.; Collab. Innov. Ctr. of Technol. and Equip. for Biol. Diagn. and Therapy in Universities of Shandong, Shandong, China; email: jinbo.pang@hotmail.com; Wang, X.; Shenzhen Key Laboratory of Nanobiomechanics, China; email: xiao.wang@siat.ac.cn; Yang, F.; Department of Chemistry, China; email: yangf3@sustech.edu.cn},
      publisher={Royal Society of Chemistry},
      issn={26335409},
      language={English},
      abbrev_source_title={Mater. Adv.},
      document_type={Article},
      source={Scopus},
      }

  • Applications of nanogenerators for biomedical engineering and healthcare systems
    • W. Wang, J. Pang, J. Su, F. Li, Q. Li, X. Wang, J. Wang, B. Ibarlucea, X. Liu, Y. Li, W. Zhou, K. Wang, Q. Han, L. Liu, R. Zang, M. H. Rümmeli, Y. Li, H. Liu, H. Hu, G. Cuniberti
    • InfoMat 4, e12262 (2022)
    • DOI   Abstract  

      The dream of human beings for long living has stimulated the rapid development of biomedical and healthcare equipment. However, conventional biomedical and healthcare devices have shortcomings such as short service life, large equipment size, and high potential safety hazards. Indeed, the power supply for conventional implantable device remains predominantly batteries. The emerging nanogenerators, which harvest micro/nanomechanical energy and thermal energy from human beings and convert into electrical energy, provide an ideal solution for self-powering of biomedical devices. The combination of nanogenerators and biomedicine has been accelerating the development of self-powered biomedical equipment. This article first introduces the operating principle of nanogenerators and then reviews the progress of nanogenerators in biomedical applications, including power supply, smart sensing, and effective treatment. Besides, the microbial disinfection and biodegradation performances of nanogenerators have been updated. Next, the protection devices have been discussed such as face mask with air filtering function together with real-time monitoring of human health from the respiration and heat emission. Besides, the nanogenerator devices have been categorized by the types of mechanical energy from human beings, such as the body movement, tissue and organ activities, energy from chemical reactions, and gravitational potential energy. Eventually, the challenges and future opportunities in the applications of nanogenerators are delivered in the conclusive remarks. (Figure presented.). © 2021 The Authors. InfoMat published by UESTC and John Wiley & Sons Australia, Ltd.

      @ARTICLE{Wang2022,
      author={Wang, W. and Pang, J. and Su, J. and Li, F. and Li, Q. and Wang, X. and Wang, J. and Ibarlucea, B. and Liu, X. and Li, Y. and Zhou, W. and Wang, K. and Han, Q. and Liu, L. and Zang, R. and Rümmeli, M.H. and Li, Y. and Liu, H. and Hu, H. and Cuniberti, G.},
      title={Applications of nanogenerators for biomedical engineering and healthcare systems},
      journal={InfoMat},
      year={2022},
      volume={4},
      number={2},
      doi={10.1002/inf2.12262},
      art_number={e12262},
      note={cited By 24},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85121372466&doi=10.1002%2finf2.12262&partnerID=40&md5=a3a7a4c385e098f420f11f831e9c47f3},
      affiliation={College of Electrical Engineering, Qingdao University, Qingdao, China; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Jinan, China; College of Electronic Information, Qingdao University, Qingdao, China; Department of Pediatric Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China; College of Physics, Qingdao University, Qingdao, China; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, Germany; College of Biological Science and Technology, University of Jinan, Jinan, China; School of Chemistry and Chemical Engineering, University of Jinan, Jinan, Shandong, China; College of Energy, Soochow Institute for Energy and Materials Innovations, Soochow University, Suzhou, China; Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, China; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, Zabrze, Poland; Institute for Complex Materials, IFW Dresden, Dresden, Germany; Institute of Environmental Technology, VŠB-Technical University of Ostrava, Ostrava, Czech Republic; School of Information Science and Engineering, University of Jinan, Jinan, China; Shandong Provincial Key Laboratory of Network Based Intelligent Computing, University of Jinan, Jinan, China; State Key Laboratory of Crystal Materials, Center of Bio & Micro/Nano Functional Materials, Shandong University, Jinan, China; College of Chemical Engineering, China University of Petroleum (East China), Qingdao, China; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany; The Dresden Center for Intelligent Materials (DCIM), Technische Universität Dresden, Dresden, Germany},
      abstract={The dream of human beings for long living has stimulated the rapid development of biomedical and healthcare equipment. However, conventional biomedical and healthcare devices have shortcomings such as short service life, large equipment size, and high potential safety hazards. Indeed, the power supply for conventional implantable device remains predominantly batteries. The emerging nanogenerators, which harvest micro/nanomechanical energy and thermal energy from human beings and convert into electrical energy, provide an ideal solution for self-powering of biomedical devices. The combination of nanogenerators and biomedicine has been accelerating the development of self-powered biomedical equipment. This article first introduces the operating principle of nanogenerators and then reviews the progress of nanogenerators in biomedical applications, including power supply, smart sensing, and effective treatment. Besides, the microbial disinfection and biodegradation performances of nanogenerators have been updated. Next, the protection devices have been discussed such as face mask with air filtering function together with real-time monitoring of human health from the respiration and heat emission. Besides, the nanogenerator devices have been categorized by the types of mechanical energy from human beings, such as the body movement, tissue and organ activities, energy from chemical reactions, and gravitational potential energy. Eventually, the challenges and future opportunities in the applications of nanogenerators are delivered in the conclusive remarks. (Figure presented.). © 2021 The Authors. InfoMat published by UESTC and John Wiley & Sons Australia, Ltd.},
      author_keywords={biomedical engineering; healthcare; implantable devices; nanogenerators; self-powered devices; sensors},
      correspondence_address1={Wang, K.; College of Electrical Engineering, China; email: wangkai@qdu.edu.cn; Pang, J.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, China; email: ifc_pangjb@ujn.edu.cn; Liu, H.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, China; email: hongliu@sdu.edu.cn; Cuniberti, G.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: gianaurelio.cuniberti@tu-dresden.de; Hu, H.; College of Chemical Engineering, China; email: hhu@upc.edu.cn},
      publisher={John Wiley and Sons Inc},
      issn={25673165},
      language={English},
      abbrev_source_title={InfoMat.},
      document_type={Review},
      source={Scopus},
      }

  • Ferromagnetic helical nodal line and Kane-Mele spin-orbit coupling in kagome metal Fe3Sn2
    • S. Fang, L. Ye, M. P. Ghimire, M. Kang, J. Liu, M. Han, L. Fu, M. Richter, J. van den Brink, E. Kaxiras, R. Comin, J. G. Checkelsky
    • Physical Review B 105, 035107 (2022)
    • DOI   Abstract  

      The two-dimensional kagome lattice hosts Dirac fermions at its Brillouin zone corners K and K′, analogous to the honeycomb lattice. In the density functional theory electronic structure of ferromagnetic kagome metal Fe3Sn2, without spin-orbit coupling, we identify two energetically split helical nodal lines winding along z in the vicinity of K and K′ resulting from the trigonal stacking of the kagome layers. We find that hopping across A-A stacking introduces a layer splitting in energy while that across A-B stacking controls the momentum space amplitude of the helical nodal lines. We identify the latter to be one order of magnitude weaker than the former owing to the underlying d-orbital degrees of freedom. The effect of spin-orbit coupling is found to resemble that of a Kane-Mele term, where the nodal lines can either be fully gapped to quasi-two-dimensional massive Dirac fermions, or remain gapless at discrete Weyl points depending on the ferromagnetic moment orientation. Aside from numerically establishing Fe3Sn2 as a model Dirac kagome metal by clarifying the roles played by interplane coupling, our results provide insights into materials design of topological phases from the lattice point of view, where paradigmatic low dimensional lattice models often find realizations in crystalline materials with three-dimensional stacking. ©2022 American Physical Society

      @ARTICLE{Fang2022,
      author={Fang, S. and Ye, L. and Ghimire, M.P. and Kang, M. and Liu, J. and Han, M. and Fu, L. and Richter, M. and van den Brink, J. and Kaxiras, E. and Comin, R. and Checkelsky, J.G.},
      title={Ferromagnetic helical nodal line and Kane-Mele spin-orbit coupling in kagome metal Fe3Sn2},
      journal={Physical Review B},
      year={2022},
      volume={105},
      number={3},
      doi={10.1103/PhysRevB.105.035107},
      art_number={035107},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85122467333&doi=10.1103%2fPhysRevB.105.035107&partnerID=40&md5=a968b6db22d711fed51cc8e71b2842cb},
      affiliation={Department of Physics and Astronomy, Center for Materials Theory, Rutgers University, Piscataway, NJ 08854, United States; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Central Department of Physics, Tribhuvan University, Kirtipur44613, Nepal; Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstraße 20, Dresden, 01069, Germany; Max Planck POSTECH Korea Research Initiative, Center for Complex Phase of Materials, Pohang, 37673, South Korea; Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, Hong Kong; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, Dresden, 01062, Germany; Department of Physics, Harvard University, Cambridge, MA 02138, United States; John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States},
      abstract={The two-dimensional kagome lattice hosts Dirac fermions at its Brillouin zone corners K and K′, analogous to the honeycomb lattice. In the density functional theory electronic structure of ferromagnetic kagome metal Fe3Sn2, without spin-orbit coupling, we identify two energetically split helical nodal lines winding along z in the vicinity of K and K′ resulting from the trigonal stacking of the kagome layers. We find that hopping across A-A stacking introduces a layer splitting in energy while that across A-B stacking controls the momentum space amplitude of the helical nodal lines. We identify the latter to be one order of magnitude weaker than the former owing to the underlying d-orbital degrees of freedom. The effect of spin-orbit coupling is found to resemble that of a Kane-Mele term, where the nodal lines can either be fully gapped to quasi-two-dimensional massive Dirac fermions, or remain gapless at discrete Weyl points depending on the ferromagnetic moment orientation. Aside from numerically establishing Fe3Sn2 as a model Dirac kagome metal by clarifying the roles played by interplane coupling, our results provide insights into materials design of topological phases from the lattice point of view, where paradigmatic low dimensional lattice models often find realizations in crystalline materials with three-dimensional stacking. ©2022 American Physical Society},
      keywords={Degrees of freedom (mechanics); Density functional theory; Electronic structure; Ferromagnetic materials; Ferromagnetism; Honeycomb structures; Iron alloys; Tin alloys; Topology, Brillouin zones; Density-functional-theory; Dirac fermions; Ferromagnetics; Honeycomb lattices; Kagome lattice; Nodal line; Spin-orbit couplings; Stackings; Two-dimensional, Binary alloys},
      publisher={American Physical Society},
      issn={24699950},
      language={English},
      abbrev_source_title={Phys. Rev. B},
      document_type={Article},
      source={Scopus},
      }

  • Applications of MXenes in human-like sensors and actuators
    • J. Pang, S. Peng, C. Hou, X. Wang, T. Wang, Y. Cao, W. Zhou, D. Sun, K. Wang, M. H. Rümmeli, G. Cuniberti, H. Liu
    • Nano Research (2022)
    • DOI   Abstract  

      Human beings perceive the world through the senses of sight, hearing, smell, taste, touch, space, and balance. The first five senses are prerequisites for people to live. The sensing organs upload information to the nervous systems, including the brain, for interpreting the surrounding environment. Then, the brain sends commands to muscles reflexively to react to stimuli, including light, gas, chemicals, sound, and pressure. MXene, as an emerging two-dimensional material, has been intensively adopted in the applications of various sensors and actuators. In this review, we update the sensors to mimic five primary senses and actuators for stimulating muscles, which employ MXene-based film, membrane, and composite with other functional materials. First, a brief introduction is delivered for the structure, properties, and synthesis methods of MXenes. Then, we feed the readers the recent reports on the MXene-derived image sensors as artificial retinas, gas sensors, chemical biosensors, acoustic devices, and tactile sensors for electronic skin. Besides, the actuators of MXene-based composite are introduced. Eventually, future opportunities are given to MXene research based on the requirements of artificial intelligence and humanoid robot, which may induce prospects in accompanying healthcare and biomedical engineering applications. [Figure not available: see fulltext.] © 2022, The Author(s).

      @ARTICLE{Pang2022,
      author={Pang, J. and Peng, S. and Hou, C. and Wang, X. and Wang, T. and Cao, Y. and Zhou, W. and Sun, D. and Wang, K. and Rümmeli, M.H. and Cuniberti, G. and Liu, H.},
      title={Applications of MXenes in human-like sensors and actuators},
      journal={Nano Research},
      year={2022},
      doi={10.1007/s12274-022-5272-8},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85142412036&doi=10.1007%2fs12274-022-5272-8&partnerID=40&md5=821a6b2ab1ca7129eb4969fd43bdbdf0},
      affiliation={Institute for Advanced Interdisciplinary Research (iAIR), Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, University of Jinan, Jinan, 250022, China; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01069, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Intelligent Materials (GCL DCIM), Technische Universität Dresden, Dresden, 01062, Germany; High-Frequency High-Voltage Device and Integrated Circuits R&D Center, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China; Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China; Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China; State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan, 250353, China; School of Bioengineering, Qilu University of Technology, Shandong Academy of Science, Jinan, 250353, China; Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology (Ministry of Education), Northeast Electric Power University, Jilin, 132012, China; School of Electrical Engineering, Northeast Electric Power University, Jilin, 132012, China; School of Electrical Engineering, Weihai Innovation Research Institute, Qingdao University, Qingdao, 266000, China; School of Electrical and Computer Engineering, Jilin Jianzhu University, Changchun, 130118, China; Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden), 20 Helmholtz Strasse, Dresden, 01069, Germany; College of Energy, Soochow Institute for Energy and Materials Innovations Soochow University, Suzhou, 215006, China; Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie Sklodowskiej 34, Zabrze, 41-819, Poland; Center for Energy and Environmental Technologies, VŠB-Technical University of Ostrava, 17. Listopadu 15, Ostrava, 708 33, Czech Republic; State Key Laboratory of Crystal Materials, Center of Bio & Micro/Nano Functional Materials, Shandong University, Jinan, 250100, China},
      abstract={Human beings perceive the world through the senses of sight, hearing, smell, taste, touch, space, and balance. The first five senses are prerequisites for people to live. The sensing organs upload information to the nervous systems, including the brain, for interpreting the surrounding environment. Then, the brain sends commands to muscles reflexively to react to stimuli, including light, gas, chemicals, sound, and pressure. MXene, as an emerging two-dimensional material, has been intensively adopted in the applications of various sensors and actuators. In this review, we update the sensors to mimic five primary senses and actuators for stimulating muscles, which employ MXene-based film, membrane, and composite with other functional materials. First, a brief introduction is delivered for the structure, properties, and synthesis methods of MXenes. Then, we feed the readers the recent reports on the MXene-derived image sensors as artificial retinas, gas sensors, chemical biosensors, acoustic devices, and tactile sensors for electronic skin. Besides, the actuators of MXene-based composite are introduced. Eventually, future opportunities are given to MXene research based on the requirements of artificial intelligence and humanoid robot, which may induce prospects in accompanying healthcare and biomedical engineering applications. [Figure not available: see fulltext.] © 2022, The Author(s).},
      author_keywords={actuators; artificial retina; biosensors; gas sensors; MXenes; sensors; sound sensors; tactile sensors},
      keywords={Anthropomorphic robots; Audition; Biomedical engineering; Biosensors; Chemical sensors; Economic and social effects; Functional materials; Gas detectors; Intelligent robots; Muscle; Tactile sensors, Artificial retinas; Five sense; Gas-sensors; Human being; Human like; Mxenes; Sensors and actuators; Sound sensors; Surrounding environment; Tactile sensors, Actuators},
      correspondence_address1={Pang, J.; Institute for Advanced Interdisciplinary Research (iAIR), China; email: ifc_pangjb@ujn.edu.cn; Liu, H.; Institute for Advanced Interdisciplinary Research (iAIR), China; email: hongliu@sdu.edu.cn; Rümmeli, M.H.; Institute for Complex Materials, 20 Helmholtz Strasse, Germany; email: m.ruemmeli@ifw-dresden.de},
      publisher={Tsinghua University},
      issn={19980124},
      language={English},
      abbrev_source_title={Nano. Res.},
      document_type={Review},
      source={Scopus},
      }

2021

  • Revised crystal structure and electronic properties of high dielectric Ba (Fe 1 / 2 Nb 1 / 2) O 3 ceramics
    • R. Ray, A. K. Himanshu, G. K. Mandal, U. Kumar, S. N. Jha, N. Patra, D. Bhattacharya, A. B. Shinde, M. Richter, P. S. R. Krishna
    • Journal of Applied Physics 130, 214101 (2021)
    • DOI   Abstract  

      Ba (Fe 1 / 2 Nb 1 / 2) O 3 ceramics are considered to be promising for technological applications owing to their high dielectric constant over a wide range of temperatures. However, there exists considerable discrepancy over the structural details. We address this discrepancy through a combined x-ray diffraction at room temperature and neutron powder diffraction measurements in the range from 5 K up to room temperature, supplemented by a comparative analysis of the earlier reported structures. Our study reveals a cubic structure with space group P m 3 ¯ m at all measured temperatures. Further, the x-ray near edge structure and extended x-ray absorption fine structure studies on the local environment of the Fe ions is consistent with the cubic symmetry. An appropriate value of U for DFT+ U calculations is obtained by comparison with x-ray absorption spectroscopy, which agrees well with the earlier reported electronic properties. © 2021 Author(s).

      @ARTICLE{Ray2021,
      author={Ray, R. and Himanshu, A.K. and Mandal, G.K. and Kumar, U. and Jha, S.N. and Patra, N. and Bhattacharya, D. and Shinde, A.B. and Richter, M. and Krishna, P.S.R.},
      title={Revised crystal structure and electronic properties of high dielectric Ba (Fe 1 / 2 Nb 1 / 2) O 3 ceramics},
      journal={Journal of Applied Physics},
      year={2021},
      volume={130},
      number={21},
      doi={10.1063/5.0068825},
      art_number={214101},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85120636887&doi=10.1063%2f5.0068825&partnerID=40&md5=cb2d426cc6e0448b1478ca93e6c2bbc3},
      affiliation={Leibniz IFW Dresden, Helmholtzstr. 20, Dresden, 01069, Germany; Variable Energy Cyclotron Center (VECC), DAE, 1/AF Bidhannagar, Kolkata, 700064, India; Department of Physics, T.M. Bhagalpur University, Bihar, Bhagalpur, 812007, India; Department of Physics, NIT Jamshedpur, Jharkhand, Jamshedpur, 831014, India; Raja Ramanna Center for Advanced Technology (RRCAT), Indore, 452013, India; Bhabha Atomic Research Center (BARC), Mumbai400085, India; Solid State Physics Division, Bhabha Atomic Research Center (BARC), Mumbai400085, India; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Homi Bhabha National Institute, Mumbai, 400094, India},
      abstract={Ba (Fe 1 / 2 Nb 1 / 2) O 3 ceramics are considered to be promising for technological applications owing to their high dielectric constant over a wide range of temperatures. However, there exists considerable discrepancy over the structural details. We address this discrepancy through a combined x-ray diffraction at room temperature and neutron powder diffraction measurements in the range from 5 K up to room temperature, supplemented by a comparative analysis of the earlier reported structures. Our study reveals a cubic structure with space group P m 3 ¯ m at all measured temperatures. Further, the x-ray near edge structure and extended x-ray absorption fine structure studies on the local environment of the Fe ions is consistent with the cubic symmetry. An appropriate value of U for DFT+ U calculations is obtained by comparison with x-ray absorption spectroscopy, which agrees well with the earlier reported electronic properties. © 2021 Author(s).},
      keywords={Crystal structure; X ray absorption spectroscopy, Combined X ray diffraction; Comparative analyzes; Crystals structures; Cubic structure; High dielectric constants; High dielectrics; Powder diffraction measurements; Space Groups; Structural details; Technological applications, Electronic properties},
      correspondence_address1={Ray, R.email: r.ray@ifw-dresden.de},
      publisher={American Institute of Physics Inc.},
      issn={00218979},
      coden={JAPIA},
      language={English},
      abbrev_source_title={J Appl Phys},
      document_type={Article},
      source={Scopus},
      }

  • Cyclic photoisomerization of azobenzene in atomistic simulations: Modeling the effect of light on columnar aggregates of azo stars
    • M. Koch, M. Saphiannikova, O. Guskova
    • Molecules 26, 7674 (2021)
    • DOI   Abstract  

      This computational study investigates the influence of light on supramolecular aggregates of three-arm azobenzene stars. Every star contains three azobenzene (azo) moieties, each able to undergo reversible photoisomerization. In solution, the azo stars build column-shaped supramolecular aggregates. Previous experimental works report severe morphological changes of these aggregates under UV–Vis light. However, the underlying molecular mechanisms are still debated. Here we aim to elucidate how light affects the structure and stability of the columnar stacks on the molecular scale. The system is investigated using fully atomistic molecular dynamics (MD) simulations. To implement the effects of light, we first developed a stochastic model of the cyclic photoisomerization of azobenzene. This model reproduces the collective photoisomerization kinetics of the azo stars in good agreement with theory and previous experiments. We then apply light of various intensities and wavelengths on an equilibrated columnar stack of azo stars in water. The simulations indicate that the aggregate does not break into separate fragments upon light irradiation. Instead, the stack develops defects in the form of molecular shifts and reorientations and, as a result, it eventually loses its columnar shape. The mechanism and driving forces behind this order–disorder structural transition are clarified based on the simulations. In the end, we provide a new interpretation of the experimentally observed morphological changes. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

      @ARTICLE{Koch2021,
      author={Koch, M. and Saphiannikova, M. and Guskova, O.},
      title={Cyclic photoisomerization of azobenzene in atomistic simulations: Modeling the effect of light on columnar aggregates of azo stars},
      journal={Molecules},
      year={2021},
      volume={26},
      number={24},
      doi={10.3390/molecules26247674},
      art_number={7674},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85121551657&doi=10.3390%2fmolecules26247674&partnerID=40&md5=a18b054a73feec8bb58dc0175803c505},
      affiliation={Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={This computational study investigates the influence of light on supramolecular aggregates of three-arm azobenzene stars. Every star contains three azobenzene (azo) moieties, each able to undergo reversible photoisomerization. In solution, the azo stars build column-shaped supramolecular aggregates. Previous experimental works report severe morphological changes of these aggregates under UV–Vis light. However, the underlying molecular mechanisms are still debated. Here we aim to elucidate how light affects the structure and stability of the columnar stacks on the molecular scale. The system is investigated using fully atomistic molecular dynamics (MD) simulations. To implement the effects of light, we first developed a stochastic model of the cyclic photoisomerization of azobenzene. This model reproduces the collective photoisomerization kinetics of the azo stars in good agreement with theory and previous experiments. We then apply light of various intensities and wavelengths on an equilibrated columnar stack of azo stars in water. The simulations indicate that the aggregate does not break into separate fragments upon light irradiation. Instead, the stack develops defects in the form of molecular shifts and reorientations and, as a result, it eventually loses its columnar shape. The mechanism and driving forces behind this order–disorder structural transition are clarified based on the simulations. In the end, we provide a new interpretation of the experimentally observed morphological changes. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.},
      author_keywords={Azobenzene; Computer simulations; Molecular dynamics; Multiphotochromic systems; Photoisomerization; Photostationary state; Supramolecular assembly},
      correspondence_address1={Koch, M.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: koch-markus@ipfdd.de; Guskova, O.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: guskova@ipfdd.de},
      publisher={MDPI},
      issn={14203049},
      coden={MOLEF},
      pubmed_id={34946756},
      language={English},
      abbrev_source_title={Molecules},
      document_type={Article},
      source={Scopus},
      }

  • Columnar aggregates of azobenzene stars: Exploring intermolecular interactions, structure, and stability in atomistic simulations
    • M. Koch, M. Saphiannikova, O. Guskova
    • Molecules 26, 7598 (2021)
    • DOI   Abstract  

      We present a simulation study of supramolecular aggregates formed by three-arm azobenzene (Azo) stars with a benzene-1,3,5-tricarboxamide (BTA) core in water. Previous experimental works by other research groups demonstrate that such Azo stars assemble into needle-like structures with light-responsive properties. Disregarding the response to light, we intend to characterize the equilibrium state of this system on the molecular scale. In particular, we aim to develop a thorough understanding of the binding mechanism between the molecules and analyze the structural properties of columnar stacks of Azo stars. Our study employs fully atomistic molecular dynamics (MD) simulations to model pre-assembled aggregates with various sizes and arrangements in water. In our detailed approach, we decompose the binding energies of the aggregates into the contributions due to the different types of non-covalent interactions and the contributions of the functional groups in the Azo stars. Initially, we investigate the origin and strength of the non-covalent interactions within a stacked dimer. Based on these findings, three arrangements of longer columnar stacks are prepared and equilibrated. We confirm that the binding energies of the stacks are mainly composed of π-π interactions between the conjugated parts of the molecules and hydrogen bonds formed between the stacked BTA cores. Our study quantifies the strength of these interactions and shows that the π-π interactions, especially between the Azo moieties, dominate the binding energies. We clarify that hydrogen bonds, which are predominant in BTA stacks, have only secondary energetic contributions in stacks of Azo stars but remain necessary stabilizers. Both types of interactions, π-π stacking and H-bonds, are required to maintain the columnar arrangement of the aggregates. © 2021 by the authors.

      @ARTICLE{Koch2021,
      author={Koch, M. and Saphiannikova, M. and Guskova, O.},
      title={Columnar aggregates of azobenzene stars: Exploring intermolecular interactions, structure, and stability in atomistic simulations},
      journal={Molecules},
      year={2021},
      volume={26},
      number={24},
      doi={10.3390/molecules26247598},
      art_number={7598},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85121537841&doi=10.3390%2fmolecules26247598&partnerID=40&md5=4de6700659415b104ef7296d754e9023},
      affiliation={Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={We present a simulation study of supramolecular aggregates formed by three-arm azobenzene (Azo) stars with a benzene-1,3,5-tricarboxamide (BTA) core in water. Previous experimental works by other research groups demonstrate that such Azo stars assemble into needle-like structures with light-responsive properties. Disregarding the response to light, we intend to characterize the equilibrium state of this system on the molecular scale. In particular, we aim to develop a thorough understanding of the binding mechanism between the molecules and analyze the structural properties of columnar stacks of Azo stars. Our study employs fully atomistic molecular dynamics (MD) simulations to model pre-assembled aggregates with various sizes and arrangements in water. In our detailed approach, we decompose the binding energies of the aggregates into the contributions due to the different types of non-covalent interactions and the contributions of the functional groups in the Azo stars. Initially, we investigate the origin and strength of the non-covalent interactions within a stacked dimer. Based on these findings, three arrangements of longer columnar stacks are prepared and equilibrated. We confirm that the binding energies of the stacks are mainly composed of π-π interactions between the conjugated parts of the molecules and hydrogen bonds formed between the stacked BTA cores. Our study quantifies the strength of these interactions and shows that the π-π interactions, especially between the Azo moieties, dominate the binding energies. We clarify that hydrogen bonds, which are predominant in BTA stacks, have only secondary energetic contributions in stacks of Azo stars but remain necessary stabilizers. Both types of interactions, π-π stacking and H-bonds, are required to maintain the columnar arrangement of the aggregates. © 2021 by the authors.},
      author_keywords={Azobenzenes; Computer simulations; Hydrogen bonding; Molecular dynamics; Supramolecular assembly},
      correspondence_address1={Koch, M.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: koch-markus@ipfdd.de},
      publisher={MDPI},
      issn={14203049},
      coden={MOLEF},
      pubmed_id={34946680},
      language={English},
      abbrev_source_title={Molecules},
      document_type={Article},
      source={Scopus},
      }

  • Faceting of Si and Ge crystals grown on deeply patterned Si substrates in the kinetic regime: phase-field modelling and experiments
    • M. Albani, R. Bergamaschini, A. Barzaghi, M. Salvalaglio, J. Valente, D. J. Paul, A. Voigt, G. Isella, F. Montalenti
    • Scientific Reports 11, 18825 (2021)
    • DOI   Abstract  

      The development of three-dimensional architectures in semiconductor technology is paving the way to new device concepts for various applications, from quantum computing to single photon avalanche detectors. In most cases, such structures are achievable only under far-from-equilibrium growth conditions. Controlling the shape and morphology of the growing structures, to meet the strict requirements for an application, is far more complex than in close-to-equilibrium cases. The development of predictive simulation tools can be essential to guide the experiments. A versatile phase-field model for kinetic crystal growth is presented and applied to the prototypical case of Ge/Si vertical microcrystals grown on deeply patterned Si substrates. These structures, under development for innovative optoelectronic applications, are characterized by a complex three-dimensional set of facets essentially driven by facet competition. First, the parameters describing the kinetics on the surface of Si and Ge are fitted on a small set of experimental results. To this goal, Si vertical microcrystals have been grown, while for Ge the fitting parameters have been obtained from data from the literature. Once calibrated, the predictive capabilities of the model are demonstrated and exploited for investigating new pattern geometries and crystal morphologies, offering a guideline for the design of new 3D heterostructures. The reported methodology is intended to be a general approach for investigating faceted growth under far-from-equilibrium conditions. © 2021, The Author(s).

      @ARTICLE{Albani2021,
      author={Albani, M. and Bergamaschini, R. and Barzaghi, A. and Salvalaglio, M. and Valente, J. and Paul, D.J. and Voigt, A. and Isella, G. and Montalenti, F.},
      title={Faceting of Si and Ge crystals grown on deeply patterned Si substrates in the kinetic regime: phase-field modelling and experiments},
      journal={Scientific Reports},
      year={2021},
      volume={11},
      number={1},
      doi={10.1038/s41598-021-98285-1},
      art_number={18825},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85115406296&doi=10.1038%2fs41598-021-98285-1&partnerID=40&md5=2577ad14bb0e17a85ca9c21bd94ad1a5},
      affiliation={L-NESS and Department of Materials Science, University of Milano - Bicocca, Milan, 20125, Italy; L-NESS and Dipartimento di Fisica, Politecnico di Milano, Como, 22100, Italy; Institute of Scientific Computing and Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; James Watt School of Engineering, University of Glasgow, Glasgow, G12 8LT, United Kingdom},
      abstract={The development of three-dimensional architectures in semiconductor technology is paving the way to new device concepts for various applications, from quantum computing to single photon avalanche detectors. In most cases, such structures are achievable only under far-from-equilibrium growth conditions. Controlling the shape and morphology of the growing structures, to meet the strict requirements for an application, is far more complex than in close-to-equilibrium cases. The development of predictive simulation tools can be essential to guide the experiments. A versatile phase-field model for kinetic crystal growth is presented and applied to the prototypical case of Ge/Si vertical microcrystals grown on deeply patterned Si substrates. These structures, under development for innovative optoelectronic applications, are characterized by a complex three-dimensional set of facets essentially driven by facet competition. First, the parameters describing the kinetics on the surface of Si and Ge are fitted on a small set of experimental results. To this goal, Si vertical microcrystals have been grown, while for Ge the fitting parameters have been obtained from data from the literature. Once calibrated, the predictive capabilities of the model are demonstrated and exploited for investigating new pattern geometries and crystal morphologies, offering a guideline for the design of new 3D heterostructures. The reported methodology is intended to be a general approach for investigating faceted growth under far-from-equilibrium conditions. © 2021, The Author(s).},
      correspondence_address1={Albani, M.; L-NESS and Department of Materials Science, Italy; email: marco.albani@unimib.it},
      publisher={Nature Research},
      issn={20452322},
      pubmed_id={34552147},
      language={English},
      abbrev_source_title={Sci. Rep.},
      document_type={Article},
      source={Scopus},
      }

  • Applications of Carbon Nanotubes in the Internet of Things Era
    • J. Pang, A. Bachmatiuk, F. Yang, H. Liu, W. Zhou, M. H. Rümmeli, G. Cuniberti
    • Nano-Micro Letters 13, 191 (2021)
    • DOI   Abstract  

      Abstract: The post-Moore’s era has boosted the progress in carbon nanotube-based transistors. Indeed, the 5G communication and cloud computing stimulate the research in applications of carbon nanotubes in electronic devices. In this perspective, we deliver the readers with the latest trends in carbon nanotube research, including high-frequency transistors, biomedical sensors and actuators, brain–machine interfaces, and flexible logic devices and energy storages. Future opportunities are given for calling on scientists and engineers into the emerging topics. [Figure not available: see fulltext.] © 2021, The Author(s).

      @ARTICLE{Pang2021,
      author={Pang, J. and Bachmatiuk, A. and Yang, F. and Liu, H. and Zhou, W. and Rümmeli, M.H. and Cuniberti, G.},
      title={Applications of Carbon Nanotubes in the Internet of Things Era},
      journal={Nano-Micro Letters},
      year={2021},
      volume={13},
      number={1},
      doi={10.1007/s40820-021-00721-4},
      art_number={191},
      note={cited By 14},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85114843798&doi=10.1007%2fs40820-021-00721-4&partnerID=40&md5=cf6dafda6d8c5605c2df550c3b5402de},
      affiliation={Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy, Institute for Advanced Interdisciplinary Research (iAIR), Universities of Shandong, University of Jinan, Shandong, Jinan 250022, China; PORT Polish Center for Technology Development, Łukasiewicz Research Network, Ul. Stabłowicka 147, Wrocław, 54-066, Poland; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie‐Sklodowskiej 34, Zabrze, 41-819, Poland; Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, China; State Key Laboratory of Crystal Materials, Center of Bio & Micro/Nano Functional Materials, Shandong University, 27 Shandanan Road, Jinan, 250100, China; College of Energy, Institute for Energy and Materials Innovations, Soochow University, Suzhou, Soochow, 215006, China; Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie Sklodowskiej 34, Zabrze, 41-819, Poland; Institute for Complex Materials, Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden), 20 Helmholtz Strasse, Dresden, 01069, Germany; Institute of Environmental Technology, VŠB-Technical University of Ostrava, 17. Listopadu 15, Ostrava, 708 33, Czech Republic; Institute for Materials Science and Max Bergmann Center of Biomaterials, Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01069, Germany; Dresden Center for Computational Materials Science, Dresden Center for Intelligent Materials (GCL DCIM), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={Abstract: The post-Moore's era has boosted the progress in carbon nanotube-based transistors. Indeed, the 5G communication and cloud computing stimulate the research in applications of carbon nanotubes in electronic devices. In this perspective, we deliver the readers with the latest trends in carbon nanotube research, including high-frequency transistors, biomedical sensors and actuators, brain–machine interfaces, and flexible logic devices and energy storages. Future opportunities are given for calling on scientists and engineers into the emerging topics. [Figure not available: see fulltext.] © 2021, The Author(s).},
      author_keywords={Actuators; Brain–machine interfaces; Carbon nanotubes; Energy storage; Sensors; Transistors},
      keywords={Biosensors; Carbon nanotubes; Computation theory; Energy storage; Internet of things; Logic devices, Biomedical sensors; Electronic device; Emerging topics; High-frequency transistors; Machine interfaces; Nanotube research; Scientists and engineers, 5G mobile communication systems},
      correspondence_address1={Pang, J.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy, China; email: jinbo.pang@hotmail.com; Cuniberti, G.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: gianaurelio.cuniberti@tu-dresden.de},
      publisher={Springer Science and Business Media B.V.},
      issn={23116706},
      language={English},
      abbrev_source_title={Nano-Micro Lett.},
      document_type={Article},
      source={Scopus},
      }

  • Applications of 2D-Layered Palladium Diselenide and Its van der Waals Heterostructures in Electronics and Optoelectronics
    • Y. Wang, J. Pang, Q. Cheng, L. Han, Y. Li, X. Meng, B. Ibarlucea, H. Zhao, F. Yang, H. Liu, H. Liu, W. Zhou, X. Wang, M. H. Rummeli, Y. Zhang, G. Cuniberti
    • Nano-Micro Letters 13, 143 (2021)
    • DOI   Abstract  

      The rapid development of two-dimensional (2D) transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties. In particular, palladium diselenide (PdSe2) with a novel pentagonal structure and unique physical characteristics have recently attracted extensive research interest. Consequently, tremendous research progress has been achieved regarding the physics, chemistry, and electronics of PdSe2. Accordingly, in this review, we recapitulate and summarize the most recent research on PdSe2, including its structure, properties, synthesis, and applications. First, a mechanical exfoliation method to obtain PdSe2 nanosheets is introduced, and large-area synthesis strategies are explained with respect to chemical vapor deposition and metal selenization. Next, the electronic and optoelectronic properties of PdSe2 and related heterostructures, such as field-effect transistors, photodetectors, sensors, and thermoelectric devices, are discussed. Subsequently, the integration of systems into infrared image sensors on the basis of PdSe2 van der Waals heterostructures is explored. Finally, future opportunities are highlighted to serve as a general guide for physicists, chemists, materials scientists, and engineers. Therefore, this comprehensive review may shed light on the research conducted by the 2D material community.[Figure not available: see fulltext.] © 2021, The Author(s).

      @ARTICLE{Wang2021,
      author={Wang, Y. and Pang, J. and Cheng, Q. and Han, L. and Li, Y. and Meng, X. and Ibarlucea, B. and Zhao, H. and Yang, F. and Liu, H. and Liu, H. and Zhou, W. and Wang, X. and Rummeli, M.H. and Zhang, Y. and Cuniberti, G.},
      title={Applications of 2D-Layered Palladium Diselenide and Its van der Waals Heterostructures in Electronics and Optoelectronics},
      journal={Nano-Micro Letters},
      year={2021},
      volume={13},
      number={1},
      doi={10.1007/s40820-021-00660-0},
      art_number={143},
      note={cited By 38},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85107978536&doi=10.1007%2fs40820-021-00660-0&partnerID=40&md5=e9573cfe8f85f28f92566d3622da7404},
      affiliation={Institute of Marine Science and Technology, Shandong University, Qingdao, 266237, China; College of Energy Soochow Institute for Energy and Materials Innovations, Soochow University, Suzhou, 215006, China; Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie Sklodowskiej 34, Zabrze, 41-819, Poland; Institute for Complex Materials, IFW Dresden 20 Helmholtz Strasse, Dresden, 01069, Germany; Institute of Environmental Technology VŠB-Technical University of Ostrava, 17. listopadu 15, Ostrava, 708 33, Czech Republic; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Shandong, Jinan 250022, China; State Key Laboratory of Crystal Materials, Center of Bio and Micro/Nano Functional Materials, Shandong University, 27 Shandanan Road, Jinan, 250100, China; Department of Chemistry, Guangdong Provincial Key Laboratory of Catalytic Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; State Key Laboratory of Advanced Materials for Smart Sensing, GRINM Group Co. Ltd., Xinwai Street 2, Beijing, 100088, China; Shenzhen Institutes of Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Avenue, Shenzhen University Town, Shenzhen, 518055, China; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01069, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Intelligent Materials (GCL DCIM), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={The rapid development of two-dimensional (2D) transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties. In particular, palladium diselenide (PdSe2) with a novel pentagonal structure and unique physical characteristics have recently attracted extensive research interest. Consequently, tremendous research progress has been achieved regarding the physics, chemistry, and electronics of PdSe2. Accordingly, in this review, we recapitulate and summarize the most recent research on PdSe2, including its structure, properties, synthesis, and applications. First, a mechanical exfoliation method to obtain PdSe2 nanosheets is introduced, and large-area synthesis strategies are explained with respect to chemical vapor deposition and metal selenization. Next, the electronic and optoelectronic properties of PdSe2 and related heterostructures, such as field-effect transistors, photodetectors, sensors, and thermoelectric devices, are discussed. Subsequently, the integration of systems into infrared image sensors on the basis of PdSe2 van der Waals heterostructures is explored. Finally, future opportunities are highlighted to serve as a general guide for physicists, chemists, materials scientists, and engineers. Therefore, this comprehensive review may shed light on the research conducted by the 2D material community.[Figure not available: see fulltext.] © 2021, The Author(s).},
      author_keywords={Field-effect transistors; nTMDC; Palladium diselenide; Photodetectors; Sensors; Synthesis},
      keywords={Chemical vapor deposition; Field effect transistors; Infrared imaging; Selenium compounds; Transition metals; Van der Waals forces, Large area synthesis; Mechanical exfoliation; Optoelectronic properties; Physical characteristics; Structure , properties; Thermoelectric devices; Transition metal dichalcogenides; Two Dimensional (2 D), Palladium compounds},
      correspondence_address1={Han, L.; Institute of Marine Science and Technology, China; email: hanlin@sdu.edu.cn; Zhang, Y.; Institute of Marine Science and Technology, China; email: yuzhang@sdu.edu.cn; Pang, J.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, China; email: ifc_pangjb@ujn.edu.cn; Liu, H.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, China; email: hongliu@sdu.edu.cn},
      publisher={Springer Science and Business Media B.V.},
      issn={23116706},
      language={English},
      abbrev_source_title={Nano-Micro Lett.},
      document_type={Review},
      source={Scopus},
      }

  • Graphene Biodevices for Early Disease Diagnosis Based on Biomarker Detection
    • Q. Han, J. Pang, Y. Li, B. Sun, B. Ibarlucea, X. Liu, T. Gemming, Q. Cheng, S. Zhang, H. Liu, J. Wang, W. Zhou, G. Cuniberti, M. H. Rümmeli
    • ACS Sensors 6, 3841-3881 (2021)
    • DOI   Abstract  

      The early diagnosis of diseases plays a vital role in healthcare and the extension of human life. Graphene-based biosensors have boosted the early diagnosis of diseases by detecting and monitoring related biomarkers, providing a better understanding of various physiological and pathological processes. They have generated tremendous interest, made significant advances, and offered promising application prospects. In this paper, we discuss the background of graphene and biosensors, including the properties and functionalization of graphene and biosensors. Second, the significant technologies adopted by biosensors are discussed, such as field-effect transistors and electrochemical and optical methods. Subsequently, we highlight biosensors for detecting various biomarkers, including ions, small molecules, macromolecules, viruses, bacteria, and living human cells. Finally, the opportunities and challenges of graphene-based biosensors and related broad research interests are discussed. ©

      @ARTICLE{Han20213841,
      author={Han, Q. and Pang, J. and Li, Y. and Sun, B. and Ibarlucea, B. and Liu, X. and Gemming, T. and Cheng, Q. and Zhang, S. and Liu, H. and Wang, J. and Zhou, W. and Cuniberti, G. and Rümmeli, M.H.},
      title={Graphene Biodevices for Early Disease Diagnosis Based on Biomarker Detection},
      journal={ACS Sensors},
      year={2021},
      volume={6},
      number={11},
      pages={3841-3881},
      doi={10.1021/acssensors.1c01172},
      note={cited By 15},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85118984824&doi=10.1021%2facssensors.1c01172&partnerID=40&md5=f3f0c3e025d02873a20e7ef131aa7b50},
      affiliation={Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy, Universities of Shandong, Institute for Advanced Interdisciplinary Research (IAIR), University of Jinan, Shandong, Jinan, 250022, China; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Intelligent Materials (GCL DCIM), Technische Universität Dresden, Dresden, 01062, Germany; Leibniz Institute for Solid State and Materials Research Dresden, Dresden, D-01171, Germany; Institute for Materials Science, Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01069, Germany; School of Biological Science and Technology, University of Jinan, 336 West Road of Nan Xinzhuang Shandong, Jinan, 250022, China; State Key Laboratory of Crystal Materials, Center of Bio and Micro/Nano Functional Materials, Shandong University, 27 Shandanan Road, Jinan, 250100, China; College of Energy, Soochow, Institute for Energy and Materials Innovations, Soochow University, Suzhou, 215006, China; Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie Sklodowskiej 34, Zabrze, 41-819, Poland; Institute of Environmental Technology (CEET), VŠB-Technical University of Ostrava, 17. Listopadu 15, Ostrava, 708 33, Czech Republic},
      abstract={The early diagnosis of diseases plays a vital role in healthcare and the extension of human life. Graphene-based biosensors have boosted the early diagnosis of diseases by detecting and monitoring related biomarkers, providing a better understanding of various physiological and pathological processes. They have generated tremendous interest, made significant advances, and offered promising application prospects. In this paper, we discuss the background of graphene and biosensors, including the properties and functionalization of graphene and biosensors. Second, the significant technologies adopted by biosensors are discussed, such as field-effect transistors and electrochemical and optical methods. Subsequently, we highlight biosensors for detecting various biomarkers, including ions, small molecules, macromolecules, viruses, bacteria, and living human cells. Finally, the opportunities and challenges of graphene-based biosensors and related broad research interests are discussed. ©},
      author_keywords={biodevices; biomarker detection; circulating tumor cells; early diagnosis; electrochemical biosensors; field-effect transistors; functionalization; graphene; microfluidic system; optical biosensors},
      keywords={Biosensors; Diagnosis; Field effect transistors; Graphene; Graphene transistors; Viruses, Bio-devices; Biomarker detection; Circulating tumour cells; Diagnoses of disease; Early diagnosis; Electrochemical biosensor; Field-effect transistor; Functionalizations; Microfluidics systems; Optical bio-sensors, Biomarkers, biological marker; graphite, early diagnosis; genetic procedures; human; virus, Biomarkers; Biosensing Techniques; Early Diagnosis; Graphite; Humans; Viruses},
      correspondence_address1={Pang, J.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy, Shandong, China; email: ifc_pangjb@ujn.edu.cn; Liu, H.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy, Shandong, China; email: hongliu@sdu.edu.cn; Cuniberti, G.; Dresden Center for Computational Materials Science, Germany; email: gianaurelio.cuniberti@tu-dresden.de; Rümmeli, M.H.; Leibniz Institute for Solid State and Materials Research DresdenGermany; email: m.ruemmeli@ifw-dresden.de},
      publisher={American Chemical Society},
      issn={23793694},
      pubmed_id={34696585},
      language={English},
      abbrev_source_title={ACS Sensors},
      document_type={Review},
      source={Scopus},
      }

  • Accessing pore microstructure–property relationships for additively manufactured materials
    • A. Raßloff, P. Schulz, R. Kühne, M. Ambati, I. Koch, A. T. Zeuner, M. Gude, M. Zimmermann, M. Kästner
    • GAMM Mitteilungen 44, e202100012 (2021)
    • DOI   Abstract  

      Understanding structure–property (SP) relationships is essential for accelerating materials innovation. Still being in the state of ongoing research and development, this is especially true for additive manufacturing (AM) in which process-induced imperfections like pores and microstructural variations significantly influence the material’s properties. That is why, the present work aims at proposing an approach for accessing pore SP relationships for AM materials. For this purpose, crystal plasticity (CP) simulations on reconstructed domains based on experimental measurements are employed to allow for a microstructure-sensitive investigation. For the considered Ti–6Al–4V specimen manufactured by laser powder bed fusion, the microstructure and pore characteristics are obtained by utilizing light microscopy and X-ray computed tomography at the microscale. Employing suitable statistical analysis and reconstruction, statistical volume elements with reconstructed pore distributions are created. Using them, microscale CP simulations are performed to obtain fatigue indicating parameters. Employing a further statistical analysis, fatigue ranking parameters are derived for a comparison of different microstructures. Additionally, a comparison with the empirical Murakami’s square root area concept is made. Results from first numerical studies underline the potential of the approach for understanding and improving AM materials. © 2021 The Authors. GAMM – Mitteilungen published by Wiley-VCH GmbH.

      @ARTICLE{Raßloff2021,
      author={Raßloff, A. and Schulz, P. and Kühne, R. and Ambati, M. and Koch, I. and Zeuner, A.T. and Gude, M. and Zimmermann, M. and Kästner, M.},
      title={Accessing pore microstructure–property relationships for additively manufactured materials},
      journal={GAMM Mitteilungen},
      year={2021},
      volume={44},
      number={4},
      doi={10.1002/gamm.202100012},
      art_number={e202100012},
      note={cited By 7},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85112117123&doi=10.1002%2fgamm.202100012&partnerID=40&md5=cfdbd374d9f58f145b035f6b3ada6747},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, Germany; Institute of Lightweight Engineering and Polymer Technology (ILK), TU Dresden, Dresden, Germany; Division Materials Characterization and Testing, Fraunhofer Institute for Material and Beam Technology (IWS), Dresden, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, Germany; Dresden Center for Fatigue and Reliability, TU Dresden, Dresden, Germany},
      abstract={Understanding structure–property (SP) relationships is essential for accelerating materials innovation. Still being in the state of ongoing research and development, this is especially true for additive manufacturing (AM) in which process-induced imperfections like pores and microstructural variations significantly influence the material's properties. That is why, the present work aims at proposing an approach for accessing pore SP relationships for AM materials. For this purpose, crystal plasticity (CP) simulations on reconstructed domains based on experimental measurements are employed to allow for a microstructure-sensitive investigation. For the considered Ti–6Al–4V specimen manufactured by laser powder bed fusion, the microstructure and pore characteristics are obtained by utilizing light microscopy and X-ray computed tomography at the microscale. Employing suitable statistical analysis and reconstruction, statistical volume elements with reconstructed pore distributions are created. Using them, microscale CP simulations are performed to obtain fatigue indicating parameters. Employing a further statistical analysis, fatigue ranking parameters are derived for a comparison of different microstructures. Additionally, a comparison with the empirical Murakami's square root area concept is made. Results from first numerical studies underline the potential of the approach for understanding and improving AM materials. © 2021 The Authors. GAMM - Mitteilungen published by Wiley-VCH GmbH.},
      author_keywords={additive manufacturing; crystal plasticity; microstructure; pores; structure–property relationships},
      keywords={3D printers; Additives; Computerized tomography; Industrial research; Microstructure; Plasticity testing; Statistical methods; Titanium metallography, Crystal plasticity; Materials innovations; Microstructural variation; Pore characteristics; Pore microstructures; Research and development; Statistical volume elements; X-ray computed tomography, Fatigue of materials},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: Markus.Kaestner@tu-dresden.de},
      publisher={John Wiley and Sons Inc},
      issn={09367195},
      language={English},
      abbrev_source_title={GAMM Mitteilungen},
      document_type={Article},
      source={Scopus},
      }

  • Modeling and simulation of interface failure in metal-composite hybrids
    • F. Hirsch, E. Natkowski, M. Kästner
    • Composites Science and Technology 214, 108965 (2021)
    • DOI   Abstract  

      The application of hybrid composites in lightweight engineering enables the combination of material-specific advantages of fiber-reinforced polymers and classical metals. The interface between the connected materials is of particular interest since failure often initializes in the bonding zone. In this contribution the connection of an aluminum component and a glass fiber-reinforced epoxy is considered on the microscale. The constitutive modeling accounts for adhesive failure of the local interfaces and cohesive failure of the bulk material. Interface failure is represented by cohesive zone models, while the behavior of the polymer is described by an elastic-plastic damage model. A gradient-enhanced formulation is applied to avoid the well-known mesh dependency of local continuum damage models. The application of numerical homogenization schemes allows for the prediction of effective traction-separation relations. Therefore, the influence of the local interface strength and geometry of random rough interfaces on the macroscopical properties is investigated in a numerical study. There is a positive effect of an increased roughness on the effective joint behavior. © 2021 Elsevier Ltd

      @ARTICLE{Hirsch2021,
      author={Hirsch, F. and Natkowski, E. and Kästner, M.},
      title={Modeling and simulation of interface failure in metal-composite hybrids},
      journal={Composites Science and Technology},
      year={2021},
      volume={214},
      doi={10.1016/j.compscitech.2021.108965},
      art_number={108965},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85113178687&doi=10.1016%2fj.compscitech.2021.108965&partnerID=40&md5=9620a1aa2b6f95a45fd18e4efb0d677a},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={The application of hybrid composites in lightweight engineering enables the combination of material-specific advantages of fiber-reinforced polymers and classical metals. The interface between the connected materials is of particular interest since failure often initializes in the bonding zone. In this contribution the connection of an aluminum component and a glass fiber-reinforced epoxy is considered on the microscale. The constitutive modeling accounts for adhesive failure of the local interfaces and cohesive failure of the bulk material. Interface failure is represented by cohesive zone models, while the behavior of the polymer is described by an elastic-plastic damage model. A gradient-enhanced formulation is applied to avoid the well-known mesh dependency of local continuum damage models. The application of numerical homogenization schemes allows for the prediction of effective traction-separation relations. Therefore, the influence of the local interface strength and geometry of random rough interfaces on the macroscopical properties is investigated in a numerical study. There is a positive effect of an increased roughness on the effective joint behavior. © 2021 Elsevier Ltd},
      author_keywords={Cohesive failure; Damage mechanics; Gradient-damage; Hybrid composites; Interface; Material modeling; Matrix cracking},
      keywords={Adhesives; Elastoplasticity; Fiber reinforced plastics; Interfaces (materials); Polymer matrix composites; Reinforcement, Cohesive failures; Damage-mechanics; Gradient damage; Hybrid composites; Interface failure; Light-weight engineering; Material models; Matrix cracking; Metal composites; Model and simulation, Failure (mechanical)},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={02663538},
      coden={CSTCE},
      language={English},
      abbrev_source_title={Compos. Sci. Technol.},
      document_type={Article},
      source={Scopus},
      }

  • Anisotropic and rate-dependent mechanical properties of 3D printed polyamide 12 – A comparison between selective laser sintering and multi jet fusion
    • F. Mehdipour, U. Gebhardt, M. Kästner
    • Results in Materials 11, 100213 (2021)
    • DOI   Abstract  

      Selective laser sintering and multi jet fusion are state-of-the-art 3D printing techniques for polymer manufacturing. In this work, the mechanical performance of 3D printed polyamide 12, which is a common material in additive manufacturing, has been studied. Specimens were printed with both – selective laser sintering and multi jet fusion technologies. Structural orientation and anisotropy of the 3D printed parts have been evaluated through studying the influence of different print orientations on the material properties. The mechanical behaviour has been concluded from tensile tests at several displacement rates. The experiments indicated a non-linear stress-strain behaviour in both cases. A more pronounced anisotropic response, as well as, a more significant rate-dependent behaviour were observed for multi jet fusion compared to selective laser sintering. In addition, laser microscopy technique was used to capture images of the fracture surface of broken specimens to evaluate similarities and differences caused by the 3D printing technologies. © 2021 The Authors

      @ARTICLE{Mehdipour2021,
      author={Mehdipour, F. and Gebhardt, U. and Kästner, M.},
      title={Anisotropic and rate-dependent mechanical properties of 3D printed polyamide 12 - A comparison between selective laser sintering and multi jet fusion},
      journal={Results in Materials},
      year={2021},
      volume={11},
      doi={10.1016/j.rinma.2021.100213},
      art_number={100213},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85126685256&doi=10.1016%2fj.rinma.2021.100213&partnerID=40&md5=fc07e26ee1ab49198cb3231ee7a5f0ce},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Dresden Center for Fatigue and Reliability (DCFR), Dresden, 01062, Germany},
      abstract={Selective laser sintering and multi jet fusion are state-of-the-art 3D printing techniques for polymer manufacturing. In this work, the mechanical performance of 3D printed polyamide 12, which is a common material in additive manufacturing, has been studied. Specimens were printed with both – selective laser sintering and multi jet fusion technologies. Structural orientation and anisotropy of the 3D printed parts have been evaluated through studying the influence of different print orientations on the material properties. The mechanical behaviour has been concluded from tensile tests at several displacement rates. The experiments indicated a non-linear stress-strain behaviour in both cases. A more pronounced anisotropic response, as well as, a more significant rate-dependent behaviour were observed for multi jet fusion compared to selective laser sintering. In addition, laser microscopy technique was used to capture images of the fracture surface of broken specimens to evaluate similarities and differences caused by the 3D printing technologies. © 2021 The Authors},
      author_keywords={Anisotropy; elective laser sintering; Laser microscopy; Multi jet fusion; Non-linear stress-strain behaviour; Polyamide 12; Rate-dependency},
      correspondence_address1={Mehdipour, F.; Institute of Solid Mechanics, Germany; email: fatemeh.mehdipour@tu-dresden.de},
      publisher={Elsevier B.V.},
      issn={2590048X},
      language={English},
      abbrev_source_title={Results Mater.},
      document_type={Article},
      source={Scopus},
      }

  • Finite temperature fluctuation-induced order and responses in magnetic topological insulators
    • M. Scholten, J. I. Facio, R. Ray, I. M. Eremin, J. van den Brink, F. S. Nogueira
    • Physical Review Research 3, L032014 (2021)
    • DOI   Abstract  

      We derive an effective field theory model for magnetic topological insulators and predict that a magnetic electronic gap persists on the surface for temperatures above the ordering temperature of the bulk. Our analysis also applies to interfaces of heterostructures consisting of a ferromagnetic and a topological insulator. In order to make quantitative predictions for  and for EuS- heterostructures, we combine the effective field theory method with density functional theory and Monte Carlo simulations. For we predict an upwards Néel temperature shift at the surface up to , while the EuS- interface exhibits a smaller relative shift. The effective theory also predicts induced Dzyaloshinskii-Moriya interactions and a topological magnetoelectric effect, both of which feature a finite temperature and chemical potential dependence. © 2021 Published by the American Physical Society

      @ARTICLE{Scholten2021,
      author={Scholten, M. and Facio, J.I. and Ray, R. and Eremin, I.M. and van den Brink, J. and Nogueira, F.S.},
      title={Finite temperature fluctuation-induced order and responses in magnetic topological insulators},
      journal={Physical Review Research},
      year={2021},
      volume={3},
      number={3},
      doi={10.1103/PhysRevResearch.3.L032014},
      art_number={L032014},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85115886858&doi=10.1103%2fPhysRevResearch.3.L032014&partnerID=40&md5=698f11072d1a05bb49d6ea9380af6404},
      affiliation={Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, Dresden, D-01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, D-01062, Germany; Institut fü, Theoretische Physik III, Ruhr-Universität Bochum, Bochum, D-44780, Germany; Institute for Theoretical Physics and Wü, rzburg-Dresden Cluster of Excellence ct.qmat, TU Dresden, Dresden, D-01069, Germany},
      abstract={We derive an effective field theory model for magnetic topological insulators and predict that a magnetic electronic gap persists on the surface for temperatures above the ordering temperature of the bulk. Our analysis also applies to interfaces of heterostructures consisting of a ferromagnetic and a topological insulator. In order to make quantitative predictions for  and for EuS- heterostructures, we combine the effective field theory method with density functional theory and Monte Carlo simulations. For we predict an upwards Néel temperature shift at the surface up to , while the EuS- interface exhibits a smaller relative shift. The effective theory also predicts induced Dzyaloshinskii-Moriya interactions and a topological magnetoelectric effect, both of which feature a finite temperature and chemical potential dependence. © 2021 Published by the American Physical Society},
      keywords={Density functional theory; Electric insulators; Forecasting; Magnetism; Monte Carlo methods; Topological insulators, Dzyaloshinskii-Moriya interaction; Effective field theory; Effective theories; Finite temperatures; Ordering temperature; Potential dependence; Quantitative prediction; Temperature shift, Topology},
      publisher={American Physical Society},
      issn={26431564},
      language={English},
      abbrev_source_title={Phys. Rev. Res.},
      document_type={Article},
      source={Scopus},
      }

  • Analysis of process-induced damage in remote laser cut carbon fibre reinforced polymers
    • B. Schmidt, M. Rose, M. Zimmermann, M. Kästner
    • Journal of Materials Processing Technology 295, 117162 (2021)
    • DOI   Abstract  

      In this paper, an approach is presented that allows for a linkage between cutting process induced damage and the mechanical properties of the machined structures. For carbon fibre reinforced polymers, the milling and remote laser cutting processes are analysed. Open hole tensile test specimens, that are either milled or remote laser cut with three different cutting parameter configurations are tested. With a two-dimensional heat conduction simulation, the temperature field resulting from laser cutting is determined and thus the thermally induced damage is quantified. Those results are compared to micro-sections. The following structural analysis is based on an anisotropic damage model and is taking the thermal pre-damage into account. For this purpose two different thermal damage modelling approaches, based on damage variables and material parameter reduction, are compared. The influence of the cutting process on the structural properties is determined and compared with experimental results. © 2021 Elsevier B.V.

      @ARTICLE{Schmidt2021,
      author={Schmidt, B. and Rose, M. and Zimmermann, M. and Kästner, M.},
      title={Analysis of process-induced damage in remote laser cut carbon fibre reinforced polymers},
      journal={Journal of Materials Processing Technology},
      year={2021},
      volume={295},
      doi={10.1016/j.jmatprotec.2021.117162},
      art_number={117162},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85103684839&doi=10.1016%2fj.jmatprotec.2021.117162&partnerID=40&md5=fce44de1b87bae944b44b6b582a8e885},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, Germany; Institute of Materials Science, TU Dresden, Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, Germany},
      abstract={In this paper, an approach is presented that allows for a linkage between cutting process induced damage and the mechanical properties of the machined structures. For carbon fibre reinforced polymers, the milling and remote laser cutting processes are analysed. Open hole tensile test specimens, that are either milled or remote laser cut with three different cutting parameter configurations are tested. With a two-dimensional heat conduction simulation, the temperature field resulting from laser cutting is determined and thus the thermally induced damage is quantified. Those results are compared to micro-sections. The following structural analysis is based on an anisotropic damage model and is taking the thermal pre-damage into account. For this purpose two different thermal damage modelling approaches, based on damage variables and material parameter reduction, are compared. The influence of the cutting process on the structural properties is determined and compared with experimental results. © 2021 Elsevier B.V.},
      author_keywords={Carbon fibre reinforced polymers; Process-structure-property linkage; Remote laser cutting; Thermal degradation},
      keywords={Bridge decks; Carbon fibers; Cutting tools; Fracture mechanics; Heat conduction; Laser beam cutting; Laser beams; Pyrolysis; Reinforcement; Tensile testing, Carbon fibre reinforced polymer; Cutting process; Laser cuts; Laser cutting process; Mechanical; Process induced damage; Process-structure-property linkage; Property; Remote laser cutting; Thermal degradation', Carbon fiber reinforced plastics},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={09240136},
      coden={JMPTE},
      language={English},
      abbrev_source_title={J Mater Process Technol},
      document_type={Article},
      source={Scopus},
      }

  • Scalable Disordered Hyperuniform Architectures via Nanoimprint Lithography of Metal Oxides
    • Z. Chehadi, M. Bouabdellaoui, M. Modaresialam, T. Bottein, M. Salvalaglio, M. Bollani, D. Grosso, M. Abbarchi
    • ACS Applied Materials and Interfaces 13, 37761-37774 (2021)
    • DOI   Abstract  

      Fabrication and scaling of disordered hyperuniform materials remain hampered by the difficulties in controlling the spontaneous phenomena leading to this novel kind of exotic arrangement of objects. Here, we demonstrate a hybrid top-down/bottom-up approach based on sol-gel dip-coating and nanoimprint lithography for the faithful reproduction of disordered hyperuniform metasurfaces in metal oxides. Nano- to microstructures made of silica and titania can be directly printed over several cm2 on glass and on silicon substrates. First, we describe the polymer mold fabrication starting from a hard master obtained via spontaneous solid-state dewetting of SiGe and Ge thin layers on SiO2. Then, we assess the effective disordered hyperuniform character of master and replica and the role of the thickness of the sol-gel layer on the metal oxide replicas and on the presence of a residual layer underneath. Finally, as a potential application, we show the antireflective character of titania structures on silicon. Our results are relevant for the realistic implementation over large scales of disordered hyperuniform nano- and microarchitectures made of metal oxides, thus opening their exploitation in the framework of wet chemical assembly. © 2021 American Chemical Society.

      @ARTICLE{Chehadi202137761,
      author={Chehadi, Z. and Bouabdellaoui, M. and Modaresialam, M. and Bottein, T. and Salvalaglio, M. and Bollani, M. and Grosso, D. and Abbarchi, M.},
      title={Scalable Disordered Hyperuniform Architectures via Nanoimprint Lithography of Metal Oxides},
      journal={ACS Applied Materials and Interfaces},
      year={2021},
      volume={13},
      number={31},
      pages={37761-37774},
      doi={10.1021/acsami.1c05779},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85112501201&doi=10.1021%2facsami.1c05779&partnerID=40&md5=b57c2e6d396e8552a12d38d8d955b513},
      affiliation={Aix Marseille Univ, Université de Toulon, CNRS, IM2NP, Marseille, France; Institute of Scientific Computing, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Istituto di Fotonica e Nanotecnologie-Consiglio Nazionale Delle Ricerche, Via Anzani 42, Como, 22100, Italy},
      abstract={Fabrication and scaling of disordered hyperuniform materials remain hampered by the difficulties in controlling the spontaneous phenomena leading to this novel kind of exotic arrangement of objects. Here, we demonstrate a hybrid top-down/bottom-up approach based on sol-gel dip-coating and nanoimprint lithography for the faithful reproduction of disordered hyperuniform metasurfaces in metal oxides. Nano- to microstructures made of silica and titania can be directly printed over several cm2 on glass and on silicon substrates. First, we describe the polymer mold fabrication starting from a hard master obtained via spontaneous solid-state dewetting of SiGe and Ge thin layers on SiO2. Then, we assess the effective disordered hyperuniform character of master and replica and the role of the thickness of the sol-gel layer on the metal oxide replicas and on the presence of a residual layer underneath. Finally, as a potential application, we show the antireflective character of titania structures on silicon. Our results are relevant for the realistic implementation over large scales of disordered hyperuniform nano- and microarchitectures made of metal oxides, thus opening their exploitation in the framework of wet chemical assembly. © 2021 American Chemical Society.},
      author_keywords={disordered hyperuniform materials; nanoimprint lithography; silica; sol-gel dip-coating; titania},
      keywords={Cell proliferation; Lithography; Metals; Si-Ge alloys; Silica; Silicon; Silicon oxides; Sol-gel process; Sol-gels; Titanium dioxide, Anti-reflective; Micro architectures; Polymer mold fabrication; Residual layers; Silicon substrates; Sol gel dip coating; Sol-gel layers; Wet chemicals, Nanoimprint lithography},
      correspondence_address1={Abbarchi, M.; Aix Marseille Univ, France; email: marco.abbarchi@im2np.fr},
      publisher={American Chemical Society},
      issn={19448244},
      pubmed_id={34320811},
      language={English},
      abbrev_source_title={ACS Appl. Mater. Interfaces},
      document_type={Article},
      source={Scopus},
      }

  • Reconstructing random heterogeneous media through differentiable optimization
    • P. Seibert, M. Ambati, A. Raßloff, M. Kästner
    • Computational Materials Science 196, 110455 (2021)
    • DOI   Abstract  

      Microstructure reconstruction is a key enabler of process-structure–property linkages, a central topic in materials engineering. Revisiting classical optimization-based reconstruction techniques, they are recognized as a powerful framework to reconstruct random heterogeneous media, especially due to their generality and controllability. The stochasticity of the available approaches is, however, identified as a performance bottleneck. In this work, reconstruction is approached as a differentiable optimization problem, where the error of a generic prescribed descriptor is minimized under consideration of its derivative. As an exemplary descriptor, a suitable differentiable version of spatial correlations is formulated, along with a multigrid scheme to ensure scalability. The applicability of differentiable optimization realized through this descriptor is demonstrated using a wide variety of heterogeneous media, achieving exact statistical equivalence with errors as low as 0% in a short time. We conclude that, while still in an early stage of development, this approach has the potential to significantly alleviate the computational effort currently associated with reconstructing general random heterogeneous media. © 2021 Elsevier B.V.

      @ARTICLE{Seibert2021,
      author={Seibert, P. and Ambati, M. and Raßloff, A. and Kästner, M.},
      title={Reconstructing random heterogeneous media through differentiable optimization},
      journal={Computational Materials Science},
      year={2021},
      volume={196},
      doi={10.1016/j.commatsci.2021.110455},
      art_number={110455},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85108691278&doi=10.1016%2fj.commatsci.2021.110455&partnerID=40&md5=124ff7d0cdeb47ddecd5ebe6e5527df3},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Dresden Center for Fatigue and Reliability, Dresden, 01062, Germany},
      abstract={Microstructure reconstruction is a key enabler of process-structure–property linkages, a central topic in materials engineering. Revisiting classical optimization-based reconstruction techniques, they are recognized as a powerful framework to reconstruct random heterogeneous media, especially due to their generality and controllability. The stochasticity of the available approaches is, however, identified as a performance bottleneck. In this work, reconstruction is approached as a differentiable optimization problem, where the error of a generic prescribed descriptor is minimized under consideration of its derivative. As an exemplary descriptor, a suitable differentiable version of spatial correlations is formulated, along with a multigrid scheme to ensure scalability. The applicability of differentiable optimization realized through this descriptor is demonstrated using a wide variety of heterogeneous media, achieving exact statistical equivalence with errors as low as 0% in a short time. We conclude that, while still in an early stage of development, this approach has the potential to significantly alleviate the computational effort currently associated with reconstructing general random heterogeneous media. © 2021 Elsevier B.V.},
      author_keywords={characterization; Descriptor; Differentiable; Gradient-based; Microstructure; Optimization; Random heterogeneous media; Reconstruction; Simulated annealing},
      keywords={Image reconstruction; Microstructure, Characterization; Descriptors; Differentiable; Gradient based; Microstructure reconstruction; Optimisations; Process structures; Random heterogeneous media; Reconstruction; Structure property, Simulated annealing},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier B.V.},
      issn={09270256},
      coden={CMMSE},
      language={English},
      abbrev_source_title={Comput Mater Sci},
      document_type={Article},
      source={Scopus},
      }

  • The role of structural symmetry on proton tautomerization: A DFTB/Meta-Dynamics computational study
    • A. Raptakis, A. Croy, A. Dianat, R. Gutierrez, G. Cuniberti
    • Chemical Physics 548, 111222 (2021)
    • DOI   Abstract  

      Porphyrins, phthalocayanines and their derivatives have found interesting applications in various fields such as molecular electronics, optoelectronics, and sensorics. Common to this class of molecules with a metal-free core is the existence of hydrogen tautomerization reactions. Since the reaction only involves the motion of a pair of hydrogen atoms, it provides a rather simple, yet non-trivial test bed for advanced simulation tools. In this investigation, we exploit state-of-the-art quantum Metadynamics simulations complemented with Nudged Elastic Band (NEB) calculations, to study the effect of structural symmetry on the proton transfer tautomerism of functionalized porphyrins and porphyrazines. Calculated activation barriers using Metadynamics and NEB show a rather good quantitative agreement. We also demonstrate that the set of chosen collective variables in the Metadynamics simulations plays an important role for the appropriate description of the reaction path and dynamics of the system. © 2021 Elsevier B.V.

      @ARTICLE{Raptakis2021,
      author={Raptakis, A. and Croy, A. and Dianat, A. and Gutierrez, R. and Cuniberti, G.},
      title={The role of structural symmetry on proton tautomerization: A DFTB/Meta-Dynamics computational study},
      journal={Chemical Physics},
      year={2021},
      volume={548},
      doi={10.1016/j.chemphys.2021.111222},
      art_number={111222},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85106970026&doi=10.1016%2fj.chemphys.2021.111222&partnerID=40&md5=e7b1e1f98653b5face9bd43e52d254f2},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={Porphyrins, phthalocayanines and their derivatives have found interesting applications in various fields such as molecular electronics, optoelectronics, and sensorics. Common to this class of molecules with a metal-free core is the existence of hydrogen tautomerization reactions. Since the reaction only involves the motion of a pair of hydrogen atoms, it provides a rather simple, yet non-trivial test bed for advanced simulation tools. In this investigation, we exploit state-of-the-art quantum Metadynamics simulations complemented with Nudged Elastic Band (NEB) calculations, to study the effect of structural symmetry on the proton transfer tautomerism of functionalized porphyrins and porphyrazines. Calculated activation barriers using Metadynamics and NEB show a rather good quantitative agreement. We also demonstrate that the set of chosen collective variables in the Metadynamics simulations plays an important role for the appropriate description of the reaction path and dynamics of the system. © 2021 Elsevier B.V.},
      correspondence_address1={Gutierrez, R.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: rafael.gutierrez@tu-dresden.de},
      publisher={Elsevier B.V.},
      issn={03010104},
      coden={CMPHC},
      language={English},
      abbrev_source_title={Chem. Phys.},
      document_type={Article},
      source={Scopus},
      }

  • 5f states in UGa2 probed by x-ray spectroscopies
    • A. V. Kolomiets, M. Paukov, J. Valenta, B. Chatterjee, A. V. Andreev, K. O. Kvashnina, F. Wilhelm, A. Rogalev, D. Drozdenko, P. Minarik, J. Kolorenč, M. Richter, J. Prchal, L. Havela
    • Physical Review B 104, 045119 (2021)
    • DOI   Abstract  

      The 5f-based ferromagnet UGa2 with the Curie temperature TC=125K was investigated by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) experiments at the U-M4,5 and Ga-K edges. The position of the U-M4 white line, determined in the high-energy resolution fluorescence detection XAS, suggests that UGa2 is neither a localized 5f2 nor an itinerant system with 5f occupancy close to n5f=3. The analysis of the acquired M4,5 XANES and XMCD spectra indicates the 5f occupancy close to 2.5 and a large orbital magnetic moment of the uranium 5f states (3.18 μB) that is partly compensated by the antiparallel spin moment (1.31 μB). Thus, the total 5f magnetic moment of 1.87 μB is obtained, which is smaller than the known bulk magnetization of 3.0 μB per formula unit, while the magnetic moments of the Ga atoms are negligible. Several methods based on density-functional theory were applied and the obtained results were compared with XAS spectral features, the Sommerfeld coefficient of the electronic specific heat, and the size of the U moments and 5f occupancies. A clear correlation is revealed between the U-M4 white-line position of three metallic uranium compounds and the calculated uranium ionicity. It is demonstrated that only electronic structure methods taking appropriate care of orbital magnetism and related atomic multiplet effects can successfully describe all considered properties. © 2021 American Physical Society.

      @ARTICLE{Kolomiets2021,
      author={Kolomiets, A.V. and Paukov, M. and Valenta, J. and Chatterjee, B. and Andreev, A.V. and Kvashnina, K.O. and Wilhelm, F. and Rogalev, A. and Drozdenko, D. and Minarik, P. and Kolorenč, J. and Richter, M. and Prchal, J. and Havela, L.},
      title={5f states in UGa2 probed by x-ray spectroscopies},
      journal={Physical Review B},
      year={2021},
      volume={104},
      number={4},
      doi={10.1103/PhysRevB.104.045119},
      art_number={045119},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85109841601&doi=10.1103%2fPhysRevB.104.045119&partnerID=40&md5=e0d364e9c4acced4d0c4d07839c42a20},
      affiliation={Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, Prague 2, 121 16, Czech Republic; Department of Physics, Lviv Polytechnic National University, 12 Bandera Str., Lviv, 79013, Ukraine; Institute of Physics, Czech Academy of Sciences, Na Slovance 2, Prague 8, 182 21, Czech Republic; Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, 01313, Germany; The Rossendorf Beamline at the European Synchrotron (ESRF), Grenoble, 38043, France; The European Synchrotron (ESRF), Grenoble, 38000, France; Leibniz IFW Dresden, Helmholtzstraße 20, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={The 5f-based ferromagnet UGa2 with the Curie temperature TC=125K was investigated by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) experiments at the U-M4,5 and Ga-K edges. The position of the U-M4 white line, determined in the high-energy resolution fluorescence detection XAS, suggests that UGa2 is neither a localized 5f2 nor an itinerant system with 5f occupancy close to n5f=3. The analysis of the acquired M4,5 XANES and XMCD spectra indicates the 5f occupancy close to 2.5 and a large orbital magnetic moment of the uranium 5f states (3.18 μB) that is partly compensated by the antiparallel spin moment (1.31 μB). Thus, the total 5f magnetic moment of 1.87 μB is obtained, which is smaller than the known bulk magnetization of 3.0 μB per formula unit, while the magnetic moments of the Ga atoms are negligible. Several methods based on density-functional theory were applied and the obtained results were compared with XAS spectral features, the Sommerfeld coefficient of the electronic specific heat, and the size of the U moments and 5f occupancies. A clear correlation is revealed between the U-M4 white-line position of three metallic uranium compounds and the calculated uranium ionicity. It is demonstrated that only electronic structure methods taking appropriate care of orbital magnetism and related atomic multiplet effects can successfully describe all considered properties. © 2021 American Physical Society.},
      keywords={Binary alloys; Circular dichroism spectroscopy; Density functional theory; Dichroism; Electronic structure; Gallium alloys; Magnetic moments; Specific heat; Uranium compounds; X ray absorption spectroscopy, Bulk magnetization; Electronic specific heat; Fluorescence detection; High-energy resolution; Orbital magnetic moment; Orbital magnetism; Sommerfeld coefficient; X-ray magnetic circular dichroism, Uranium metallography},
      publisher={American Physical Society},
      issn={24699950},
      language={English},
      abbrev_source_title={Phys. Rev. B},
      document_type={Article},
      source={Scopus},
      }

  • An Atomistic Study of the Thermoelectric Signatures of CNT Peapods
    • A. Rodríguez Méndez, L. Medrano Sandonas, A. Dianat, R. Gutierrez, G. Cuniberti
    • Journal of Physical Chemistry C 125, 13721-13731 (2021)
    • DOI   Abstract  

      Carbon-based nanomaterials such as carbon nanotubes (CNTs) have a great potential for applications in the development of high performance thermoelectric (TE) materials because of their low-cost and for being environmentally friendly. Pristine nanotubes have, however, high electrical and thermal conductivities so that further nanoscale engineering is required to exploit them as TE materials. We investigate electron and phonon transport in CNT peapods to elucidate their potential advantage over pristine CNTs as basic TE elements. We show that the electron and phonon transport properties are sensitively modified by C60encapsulation, when the CNT-C60intermolecular interaction is strong enough to produce a periodic buckling of the CNT walls. Moreover, the phonon transmission is strongly suppressed at low and high frequencies, leading to a reduction of the phonon contribution to the overall thermal conductance. A similar effect has also been observed in the recently proposed phononic metamaterials. We obtain in general a larger TE figure of merit over a broad temperature range for the CNT peapod when compared with the pristine CNT, achieving an increase by a factor of 2.2 at 575 K. Our findings show an alternative route for the enhancement of the TE performance of CNT-based devices. © 2021 American Chemical Society

      @ARTICLE{RodríguezMéndez202113721,
      author={Rodríguez Méndez, A. and Medrano Sandonas, L. and Dianat, A. and Gutierrez, R. and Cuniberti, G.},
      title={An Atomistic Study of the Thermoelectric Signatures of CNT Peapods},
      journal={Journal of Physical Chemistry C},
      year={2021},
      volume={125},
      number={25},
      pages={13721-13731},
      doi={10.1021/acs.jpcc.1c02611},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85110504330&doi=10.1021%2facs.jpcc.1c02611&partnerID=40&md5=93b4d9f5ea1f024b64d8e53823352f36},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Department of Physics and Materials Science, University of Luxembourg, Luxembourg, L-1511, Luxembourg; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Carbon-based nanomaterials such as carbon nanotubes (CNTs) have a great potential for applications in the development of high performance thermoelectric (TE) materials because of their low-cost and for being environmentally friendly. Pristine nanotubes have, however, high electrical and thermal conductivities so that further nanoscale engineering is required to exploit them as TE materials. We investigate electron and phonon transport in CNT peapods to elucidate their potential advantage over pristine CNTs as basic TE elements. We show that the electron and phonon transport properties are sensitively modified by C60encapsulation, when the CNT-C60intermolecular interaction is strong enough to produce a periodic buckling of the CNT walls. Moreover, the phonon transmission is strongly suppressed at low and high frequencies, leading to a reduction of the phonon contribution to the overall thermal conductance. A similar effect has also been observed in the recently proposed phononic metamaterials. We obtain in general a larger TE figure of merit over a broad temperature range for the CNT peapod when compared with the pristine CNT, achieving an increase by a factor of 2.2 at 575 K. Our findings show an alternative route for the enhancement of the TE performance of CNT-based devices. © 2021 American Chemical Society},
      keywords={Phonons; Thermal conductivity; Thermal Engineering, Broad temperature ranges; Electron and phonon transports; Intermolecular interactions; Low and high frequencies; Nanoscale engineering; Phonon transmissions; Thermal conductance; Thermoelectric material, Carbon nanotubes},
      correspondence_address1={Gutierrez, R.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: rafael.gutierrez@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19327447},
      language={English},
      abbrev_source_title={J. Phys. Chem. C},
      document_type={Article},
      source={Scopus},
      }

  • Multiscale Modeling Strategy of 2D Covalent Organic Frameworks Confined at an Air-Water Interface
    • A. Ortega-Guerrero, H. Sahabudeen, A. Croy, A. Dianat, R. Dong, X. Feng, G. Cuniberti
    • ACS Applied Materials and Interfaces 13, 26411-26420 (2021)
    • DOI   Abstract  

      Two-dimensional covalent organic frameworks (2D COFs) have attracted attention as versatile active materials in many applications. Recent advances have demonstrated the synthesis of monolayer 2D COF via an air-water interface. However, the interfacial 2D polymerization mechanism has been elusive. In this work, we have used a multiscale modeling strategy to study dimethylmethylene-bridged triphenylamine building blocks confined at the air-water interface to form a 2D COF via Schiff-base reaction. A synergy between the computational investigations and experiments allowed the synthesis of a 2D-COF with one of the linkers considered. Our simulations complement the experimental characterization and show the preference of the building blocks to be at the interface with a favorable orientation for the polymerization. The air-water interface is shown to be a key factor to stabilize a flat conformation when a dimer molecule is considered. The structural and electronic properties of the monolayer COFs based on the two monomers are calculated and show a semiconducting nature with direct bandgaps. Our strategy provides a first step toward the in silico polymerization of 2D COFs at air-water interfaces capturing the initial steps of the synthesis up to the prediction of electronic properties of the 2D material. © 2021 American Chemical Society.

      @ARTICLE{Ortega-Guerrero202126411,
      author={Ortega-Guerrero, A. and Sahabudeen, H. and Croy, A. and Dianat, A. and Dong, R. and Feng, X. and Cuniberti, G.},
      title={Multiscale Modeling Strategy of 2D Covalent Organic Frameworks Confined at an Air-Water Interface},
      journal={ACS Applied Materials and Interfaces},
      year={2021},
      volume={13},
      number={22},
      pages={26411-26420},
      doi={10.1021/acsami.1c05967},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85108020271&doi=10.1021%2facsami.1c05967&partnerID=40&md5=6fcea09f89d8728fb6a25012121eabbc},
      affiliation={Laboratory of Molecular Simulation (LSMO), Institut des Sciences et Ingénierie Chimiques, Valais Ecole Polytechnique Fédérale de Lausanne (EPFL), Rue de l'Industrie 17, Valais, Sion, CH-1951, Switzerland; Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden (CFAED), Technische Universität Dresden, Dresden, 01062, Germany; Institute for Materials Science, Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Institute of Active Polymers, Helmholtz-Zentrum Hereon, Teltow, 14513, Germany},
      abstract={Two-dimensional covalent organic frameworks (2D COFs) have attracted attention as versatile active materials in many applications. Recent advances have demonstrated the synthesis of monolayer 2D COF via an air-water interface. However, the interfacial 2D polymerization mechanism has been elusive. In this work, we have used a multiscale modeling strategy to study dimethylmethylene-bridged triphenylamine building blocks confined at the air-water interface to form a 2D COF via Schiff-base reaction. A synergy between the computational investigations and experiments allowed the synthesis of a 2D-COF with one of the linkers considered. Our simulations complement the experimental characterization and show the preference of the building blocks to be at the interface with a favorable orientation for the polymerization. The air-water interface is shown to be a key factor to stabilize a flat conformation when a dimer molecule is considered. The structural and electronic properties of the monolayer COFs based on the two monomers are calculated and show a semiconducting nature with direct bandgaps. Our strategy provides a first step toward the in silico polymerization of 2D COFs at air-water interfaces capturing the initial steps of the synthesis up to the prediction of electronic properties of the 2D material. © 2021 American Chemical Society.},
      author_keywords={azine linkage; covalent organic frameworks; DFT(B); Langmuir-Blodgett; MD; Schiff base reactions},
      keywords={Air; Dimers; Electronic properties; Monolayers; Polymerization; Solute transport, Air water interfaces; Computational investigation; Covalent organic frameworks; Experimental characterization; Multi-scale Modeling; Polymerization mechanisms; Schiff base reaction; Structural and electronic properties, Phase interfaces},
      correspondence_address1={Cuniberti, G.; Institute for Materials Science, Germany; email: gianaurelio.cuniberti@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19448244},
      pubmed_id={34034486},
      language={English},
      abbrev_source_title={ACS Appl. Mater. Interfaces},
      document_type={Article},
      source={Scopus},
      }

  • Strongly anisotropic spin dynamics in magnetic topological insulators
    • A. Alfonsov, J. I. Facio, K. Mehlawat, A. G. Moghaddam, R. Ray, A. Zeugner, M. Richter, J. Van Den Brink, A. Isaeva, B. Büchner, V. Kataev
    • Physical Review B 103, L180403 (2021)
    • DOI   Abstract  

      The recent discovery of magnetic topological insulators has opened new avenues to explore exotic states of matter that can emerge from the interplay between topological electronic states and magnetic degrees of freedom, be it ordered or strongly fluctuating. Motivated by the effects that the dynamics of the magnetic moments can have on the topological surface states, we investigate the magnetic fluctuations across the (MnBi2Te4)(Bi2Te3)n family. Our paramagnetic electron spin resonance experiments reveal contrasting Mn spin dynamics in different compounds, which manifests in a strongly anisotropic Mn spin relaxation in MnBi2Te4 while being almost isotropic in MnBi4Te7. Our density-functional calculations explain these striking observations in terms of the sensitivity of the local electronic structure to the Mn spin orientation, and indicate that the anisotropy of the magnetic fluctuations can be controlled by the carrier density, which may directly affect the electronic topological surface states. © 2021 American Physical Society.

      @ARTICLE{Alfonsov2021,
      author={Alfonsov, A. and Facio, J.I. and Mehlawat, K. and Moghaddam, A.G. and Ray, R. and Zeugner, A. and Richter, M. and Van Den Brink, J. and Isaeva, A. and Büchner, B. and Kataev, V.},
      title={Strongly anisotropic spin dynamics in magnetic topological insulators},
      journal={Physical Review B},
      year={2021},
      volume={103},
      number={18},
      doi={10.1103/PhysRevB.103.L180403},
      art_number={L180403},
      note={cited By 7},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85107285144&doi=10.1103%2fPhysRevB.103.L180403&partnerID=40&md5=04421bfe9c860cf3dffac4d09471f1bf},
      affiliation={Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, D-01069, Germany; Würzburg-Dresden Cluster of Excellence, TU Dresden, Dresden, D-01062, Germany; Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, 45137-66731, Iran; Faculty of Chemistry and Food Chemistry, TU Dresden, Dresden, D-01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, D-01062, Germany; Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Amsterdam, 1098 XH, Netherlands},
      abstract={The recent discovery of magnetic topological insulators has opened new avenues to explore exotic states of matter that can emerge from the interplay between topological electronic states and magnetic degrees of freedom, be it ordered or strongly fluctuating. Motivated by the effects that the dynamics of the magnetic moments can have on the topological surface states, we investigate the magnetic fluctuations across the (MnBi2Te4)(Bi2Te3)n family. Our paramagnetic electron spin resonance experiments reveal contrasting Mn spin dynamics in different compounds, which manifests in a strongly anisotropic Mn spin relaxation in MnBi2Te4 while being almost isotropic in MnBi4Te7. Our density-functional calculations explain these striking observations in terms of the sensitivity of the local electronic structure to the Mn spin orientation, and indicate that the anisotropy of the magnetic fluctuations can be controlled by the carrier density, which may directly affect the electronic topological surface states. © 2021 American Physical Society.},
      keywords={Bismuth compounds; Degrees of freedom (mechanics); Electric insulators; Electronic structure; Electrospinning; Magnetic anisotropy; Magnetic moments; Surface states; Tellurium compounds; Topology, Exotic state; Local electronic structures; Magnetic fluctuation; Mn spin relaxation; Spin orientations, Spin fluctuations},
      publisher={American Physical Society},
      issn={24699950},
      language={English},
      abbrev_source_title={Phys. Rev. B},
      document_type={Article},
      source={Scopus},
      }

  • Doubly degenerate diffuse interface models of anisotropic surface diffusion
    • M. Salvalaglio, M. Selch, A. Voigt, S. M. Wise
    • Mathematical Methods in the Applied Sciences 44, 5406-5417 (2021)
    • DOI   Abstract  

      We extend the doubly degenerate Cahn–Hilliard (DDCH) models for isotropic surface diffusion, which yield more accurate approximations than classical degenerate Cahn–Hilliard (DCH) models, to the anisotropic case. We consider both weak and strong anisotropies and demonstrate the capabilities of the approach for these cases numerically. The proposed model provides a variational and energy dissipative approach for anisotropic surface diffusion, enabling large-scale simulations with material-specific parameters. © 2020 The Authors. Mathematical Methods in the Applied Sciences published by John Wiley & Sons Ltd

      @ARTICLE{Salvalaglio20215406,
      author={Salvalaglio, M. and Selch, M. and Voigt, A. and Wise, S.M.},
      title={Doubly degenerate diffuse interface models of anisotropic surface diffusion},
      journal={Mathematical Methods in the Applied Sciences},
      year={2021},
      volume={44},
      number={7},
      pages={5406-5417},
      doi={10.1002/mma.7118},
      note={cited By 6},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85097852332&doi=10.1002%2fmma.7118&partnerID=40&md5=686693570aacd1683dc69ec85b7b87ce},
      affiliation={Institute of Scientific Computing, Department of Mathematics, TU Dresden, Dresden, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, Germany; Department of Mathematics, The University of Tennessee, Knoxville, TN, United States},
      abstract={We extend the doubly degenerate Cahn–Hilliard (DDCH) models for isotropic surface diffusion, which yield more accurate approximations than classical degenerate Cahn–Hilliard (DCH) models, to the anisotropic case. We consider both weak and strong anisotropies and demonstrate the capabilities of the approach for these cases numerically. The proposed model provides a variational and energy dissipative approach for anisotropic surface diffusion, enabling large-scale simulations with material-specific parameters. © 2020 The Authors. Mathematical Methods in the Applied Sciences published by John Wiley & Sons Ltd},
      author_keywords={anisotropy; degenerate Cahn–Hilliard equation; surface diffusion},
      keywords={Surface diffusion, Anisotropic surface diffusion; Diffuse interface models; Isotropic surfaces; Large scale simulations; Strong anisotropy, Anisotropy},
      correspondence_address1={Salvalaglio, M.; Institute of Scientific Computing, Germany; email: marco.salvalaglio@tu-dresden.de; Salvalaglio, M.; Dresden Center for Computational Materials Science, Germany; email: marco.salvalaglio@tu-dresden.de},
      publisher={John Wiley and Sons Ltd},
      issn={01704214},
      coden={MMSCD},
      language={English},
      abbrev_source_title={Math Methods Appl Sci},
      document_type={Article},
      source={Scopus},
      }

  • Mesoscale Defect Motion in Binary Systems: Effects of Compositional Strain and Cottrell Atmospheres
    • M. Salvalaglio, A. Voigt, Z. -F. Huang, K. R. Elder
    • Physical Review Letters 126, 185502 (2021)
    • DOI   Abstract  

      The velocity of dislocations is derived analytically to incorporate and predict the intriguing effects induced by the preferential solute segregation and Cottrell atmospheres in both two-dimensional and three-dimensional binary systems of various crystalline symmetries. The corresponding mesoscopic description of defect dynamics is constructed through the amplitude formulation of the phase-field crystal model, which has been shown to accurately capture elasticity and plasticity in a wide variety of systems. Modifications of the Peach-Koehler force as a result of solute concentration variations and compositional stresses are presented, leading to interesting new predictions of defect motion due to effects of Cottrell atmospheres. These include the deflection of dislocation glide paths, the variation of climb speed and direction, and the change or prevention of defect annihilation, all of which play an important role in determining the fundamental behaviors of complex defect network and dynamics. The analytic results are verified by numerical simulations. © 2021 American Physical Society.

      @ARTICLE{Salvalaglio2021,
      author={Salvalaglio, M. and Voigt, A. and Huang, Z.-F. and Elder, K.R.},
      title={Mesoscale Defect Motion in Binary Systems: Effects of Compositional Strain and Cottrell Atmospheres},
      journal={Physical Review Letters},
      year={2021},
      volume={126},
      number={18},
      doi={10.1103/PhysRevLett.126.185502},
      art_number={185502},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85105741553&doi=10.1103%2fPhysRevLett.126.185502&partnerID=40&md5=31b8c81fa96ca67936995f7ab92896f8},
      affiliation={Institute of Scientific Computing, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, United States; Department of Physics, Oakland University, Rochester, MI 48309, United States},
      abstract={The velocity of dislocations is derived analytically to incorporate and predict the intriguing effects induced by the preferential solute segregation and Cottrell atmospheres in both two-dimensional and three-dimensional binary systems of various crystalline symmetries. The corresponding mesoscopic description of defect dynamics is constructed through the amplitude formulation of the phase-field crystal model, which has been shown to accurately capture elasticity and plasticity in a wide variety of systems. Modifications of the Peach-Koehler force as a result of solute concentration variations and compositional stresses are presented, leading to interesting new predictions of defect motion due to effects of Cottrell atmospheres. These include the deflection of dislocation glide paths, the variation of climb speed and direction, and the change or prevention of defect annihilation, all of which play an important role in determining the fundamental behaviors of complex defect network and dynamics. The analytic results are verified by numerical simulations. © 2021 American Physical Society.},
      keywords={Systems (metallurgical), Cottrell atmospheres; Crystalline symmetry; Defect annihilation; Dislocation glide; Peach-Koehler forces; Phase field crystal model; Solute concentrations; Solute segregation, Defects},
      correspondence_address1={Salvalaglio, M.; Institute of Scientific Computing, Germany; email: marco.salvalaglio@tu-dresden.de},
      publisher={American Physical Society},
      issn={00319007},
      coden={PRLTA},
      pubmed_id={34018767},
      language={English},
      abbrev_source_title={Phys Rev Lett},
      document_type={Article},
      source={Scopus},
      }

  • Determining the Diffusion Coefficient of Lithium Insertion Cathodes from GITT measurements: Theoretical Analysis for low Temperatures**
    • T. Schied, A. Nickol, C. Heubner, M. Schneider, A. Michaelis, M. Bobeth, G. Cuniberti
    • ChemPhysChem 22, 885-893 (2021)
    • DOI   Abstract  

      Accurate knowledge of transport properties of Li-insertion materials in application-relevant temperature ranges is of crucial importance for the targeted optimization of Li-ion batteries (LIBs). Galvanostatic intermittent titration technique (GITT) is a widely applied method to determine Li-ion diffusion coefficients of electrode materials. The well-known calculation formulas based on Weppner’s and Huggins’ approach, imply a square-root time dependence of the potential during a GITT pulse. Charging the electrochemical double layer capacitance at the beginning of a GITT pulse usually takes less than one second. However, at lower temperatures down to −40 °C, the double layer charging time strongly increases due to an increase of the charge transfer resistance. The charging time can become comparable with the pulse duration, impeding the conventional GITT diffusion analysis. We propose a model to describe the potential change during a galvanostatic current pulse, which includes an initial, relatively long-lasting double layer charging, and analyze the accuracy of the lithium diffusion coefficient, derived by using the Weppner-Huggins method within a suitably chosen time interval of the pulse. Effects leading to an inaccurate determination of the diffusion coefficient are discussed and suggestions to improve GITT analyses at low temperature are derived. © 2021 The Authors. ChemPhysChem published by Wiley-VCH GmbH

      @ARTICLE{Schied2021885,
      author={Schied, T. and Nickol, A. and Heubner, C. and Schneider, M. and Michaelis, A. and Bobeth, M. and Cuniberti, G.},
      title={Determining the Diffusion Coefficient of Lithium Insertion Cathodes from GITT measurements: Theoretical Analysis for low Temperatures**},
      journal={ChemPhysChem},
      year={2021},
      volume={22},
      number={9},
      pages={885-893},
      doi={10.1002/cphc.202001025},
      note={cited By 15},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85104242079&doi=10.1002%2fcphc.202001025&partnerID=40&md5=4ca2f07390cb9780f83f335a9025cf8b},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Fraunhofer IKTS Dresden, Winterbergstr. 28, Dresden, 01277, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Accurate knowledge of transport properties of Li-insertion materials in application-relevant temperature ranges is of crucial importance for the targeted optimization of Li-ion batteries (LIBs). Galvanostatic intermittent titration technique (GITT) is a widely applied method to determine Li-ion diffusion coefficients of electrode materials. The well-known calculation formulas based on Weppner's and Huggins’ approach, imply a square-root time dependence of the potential during a GITT pulse. Charging the electrochemical double layer capacitance at the beginning of a GITT pulse usually takes less than one second. However, at lower temperatures down to −40 °C, the double layer charging time strongly increases due to an increase of the charge transfer resistance. The charging time can become comparable with the pulse duration, impeding the conventional GITT diffusion analysis. We propose a model to describe the potential change during a galvanostatic current pulse, which includes an initial, relatively long-lasting double layer charging, and analyze the accuracy of the lithium diffusion coefficient, derived by using the Weppner-Huggins method within a suitably chosen time interval of the pulse. Effects leading to an inaccurate determination of the diffusion coefficient are discussed and suggestions to improve GITT analyses at low temperature are derived. © 2021 The Authors. ChemPhysChem published by Wiley-VCH GmbH},
      author_keywords={Battery; charge transfer; diffusion coefficient of cathode material; galvanostatic intermittent titration technique; low temperature kinetics},
      keywords={Cathodes; Charge transfer; Charging time; Electrochemical electrodes; Lithium-ion batteries; Temperature, Calculation formula; Charge transfer resistance; Double layer charging; Double-layer capacitance; Galvanostatic current; Galvanostatic Intermittent Titration Techniques; Ion diffusion coefficient; Targeted optimization, Diffusion},
      correspondence_address1={Schied, T.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: thomas.schied@tu-dresden.de; Cuniberti, G.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: gianaurelio.cuniberti@tu-dresden.de},
      publisher={John Wiley and Sons Inc},
      issn={14394235},
      coden={CPCHF},
      pubmed_id={33615633},
      language={English},
      abbrev_source_title={ChemPhysChem},
      document_type={Article},
      source={Scopus},
      }

  • Benchmark for the coupled magneto-mechanical boundary value problem in magneto-active elastomers
    • P. Metsch, R. Schiedung, I. Steinbach, M. Kästner
    • Materials 14, 2380 (2021)
    • DOI   Abstract  

      Within this contribution, a novel benchmark problem for the coupled magneto-mechanical boundary value problem in magneto-active elastomers is presented. Being derived from an experimental analysis of magnetically induced interactions in these materials, the problem under investigation allows us to validate different modeling strategies by means of a simple setup with only a few influencing factors. Here, results of a sharp-interface Lagrangian finite element framework and a diffuse-interface Eulerian approach based on the application of a spectral solver on a fixed grid are compared for the simplified two-dimensional as well as the general three-dimensional case. After influences of different boundary conditions and the sample size are analyzed, the results of both strategies are examined: For the material models under consideration, a good agreement of them is found, while all discrepancies can be ascribed to well-known effects described in the literature. Thus, the benchmark problem can be seen as a basis for future comparisons with both other modeling strategies and more elaborate material models. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

      @ARTICLE{Metsch2021,
      author={Metsch, P. and Schiedung, R. and Steinbach, I. and Kästner, M.},
      title={Benchmark for the coupled magneto-mechanical boundary value problem in magneto-active elastomers},
      journal={Materials},
      year={2021},
      volume={14},
      number={9},
      doi={10.3390/ma14092380},
      art_number={2380},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85105681944&doi=10.3390%2fma14092380&partnerID=40&md5=376b4fe5a993d7bbd325ce14a7b93936},
      affiliation={Institute of Solid Mechanics, Technische Universität Dresden, Dresden, 01062, Germany; ICAMS, Ruhr-University Bochum, Bochum, 44801, Germany; National Institute for Materials Science (NIMS), Tsukuba, 305-0044, Japan; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={Within this contribution, a novel benchmark problem for the coupled magneto-mechanical boundary value problem in magneto-active elastomers is presented. Being derived from an experimental analysis of magnetically induced interactions in these materials, the problem under investigation allows us to validate different modeling strategies by means of a simple setup with only a few influencing factors. Here, results of a sharp-interface Lagrangian finite element framework and a diffuse-interface Eulerian approach based on the application of a spectral solver on a fixed grid are compared for the simplified two-dimensional as well as the general three-dimensional case. After influences of different boundary conditions and the sample size are analyzed, the results of both strategies are examined: For the material models under consideration, a good agreement of them is found, while all discrepancies can be ascribed to well-known effects described in the literature. Thus, the benchmark problem can be seen as a basis for future comparisons with both other modeling strategies and more elaborate material models. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.},
      author_keywords={Benchmark; Magneto-active elastomers; Strong magneto-mechanical coupling},
      keywords={Benchmarking; Elastomers, Bench-mark problems; Different boundary condition; Diffuse interface; Eulerian approach; Experimental analysis; Induced interaction; Mechanical boundaries; Modeling strategy, Boundary value problems},
      correspondence_address1={Schiedung, R.; ICAMS, Germany; email: raphael.schiedung@rub.de},
      publisher={MDPI AG},
      issn={19961944},
      language={English},
      abbrev_source_title={Mater.},
      document_type={Article},
      source={Scopus},
      }

  • Thermoelectric energy harvesting from single-walled carbon nanotube alkali-activated nanocomposites produced from industrial waste materials
    • M. Davoodabadi, I. Vareli, M. Liebscher, L. Tzounis, M. Sgarzi, A. S. Paipetis, J. Yang, G. Cuniberti, V. Mechtcherine
    • Nanomaterials 11, 1095 (2021)
    • DOI   Abstract  

      A waste-originated one-part alkali-activated nanocomposite is introduced herein as a novel thermoelectric material. For this purpose, single-walled carbon nanotubes (SWCNTs) were utilized as nanoinclusions to create an electrically conductive network within the investigated alkali-activated construction material. Thermoelectric and microstructure characteristics of SWCNT-alkali-activated nanocomposites were assessed after 28 days. Nanocomposites with 1.0 wt.% SWCNTs exhibited a multifunctional behavior, a combination of structural load-bearing, electrical conductivity, and thermoelectric response. These nanocomposites (1.0 wt.%) achieved the highest thermoelectric performance in terms of power factor (PF), compared to the lower SWCNTs’ incorporations, namely 0.1 and 0.5 wt.%. The measured electrical conductivity (σ) and Seebeck coefficient (S) were 1660 S·m−1 and 15.8 µV·K−1, respectively, which led to a power factor of 0.414 µW·m−1·K−2 . Consequently, they have been utilized as the building block of a thermoelectric generator (TEG) device, which demon-strated a maximum power output (Pout ) of 0.695 µW, with a power density (PD) of 372 nW·m−2, upon exposure to a temperature gradient of 60 K. The presented SWCNT-alkali-activated nanocomposites could establish the pathway towards waste thermal energy harvesting and future sustainable civil engineering structures. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

      @ARTICLE{Davoodabadi2021,
      author={Davoodabadi, M. and Vareli, I. and Liebscher, M. and Tzounis, L. and Sgarzi, M. and Paipetis, A.S. and Yang, J. and Cuniberti, G. and Mechtcherine, V.},
      title={Thermoelectric energy harvesting from single-walled carbon nanotube alkali-activated nanocomposites produced from industrial waste materials},
      journal={Nanomaterials},
      year={2021},
      volume={11},
      number={5},
      doi={10.3390/nano11051095},
      art_number={1095},
      note={cited By 6},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85104503827&doi=10.3390%2fnano11051095&partnerID=40&md5=4d65f2c8ddfa0afa9d0936ce211163b6},
      affiliation={Institute of Construction Materials, Faculty of Civil Engineering, Dresden University of Technology, Dresden, 01069, Germany; Institute for Materials Science and Max Bergmann Centre of Biomaterials, Dresden University of Technology, Dresden, 01069, Germany; Dresden Center for Nanoanalysis (DCN), Dresden University of Technology, Dresden, 01069, Germany; Department of Civil Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China; Department of Materials Science and Engineering, University of Ioannina, Ioannina, 45110, Greece; Center for Advancing Electronics Dresden (CfAED), Dresden University of Technology, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Dresden University of Technology, Dresden, 01069, Germany},
      abstract={A waste-originated one-part alkali-activated nanocomposite is introduced herein as a novel thermoelectric material. For this purpose, single-walled carbon nanotubes (SWCNTs) were utilized as nanoinclusions to create an electrically conductive network within the investigated alkali-activated construction material. Thermoelectric and microstructure characteristics of SWCNT-alkali-activated nanocomposites were assessed after 28 days. Nanocomposites with 1.0 wt.% SWCNTs exhibited a multifunctional behavior, a combination of structural load-bearing, electrical conductivity, and thermoelectric response. These nanocomposites (1.0 wt.%) achieved the highest thermoelectric performance in terms of power factor (PF), compared to the lower SWCNTs’ incorporations, namely 0.1 and 0.5 wt.%. The measured electrical conductivity (σ) and Seebeck coefficient (S) were 1660 S·m−1 and 15.8 µV·K−1, respectively, which led to a power factor of 0.414 µW·m−1·K−2 . Consequently, they have been utilized as the building block of a thermoelectric generator (TEG) device, which demon-strated a maximum power output (Pout ) of 0.695 µW, with a power density (PD) of 372 nW·m−2, upon exposure to a temperature gradient of 60 K. The presented SWCNT-alkali-activated nanocomposites could establish the pathway towards waste thermal energy harvesting and future sustainable civil engineering structures. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.},
      author_keywords={Alkali-activated nanocomposites; Green construction; Multifunctional waste materials; Single-walled carbon nanotubes; Thermal energy harvesting; Thermoelectric generator},
      correspondence_address1={Liebscher, M.; Institute of Construction Materials, Germany; email: marco.liebscher@tu-dresden.de; Tzounis, L.; Department of Materials Science and Engineering, Greece; email: latzounis@uoi.gr},
      publisher={MDPI AG},
      issn={20794991},
      language={English},
      abbrev_source_title={Nanomaterials},
      document_type={Article},
      source={Scopus},
      }

  • Orbital Complexity in Intrinsic Magnetic Topological Insulators MnBi4Te7 and MnBi6Te10
    • R. C. Vidal, H. Bentmann, J. I. Facio, T. Heider, P. Kagerer, C. I. Fornari, T. R. F. Peixoto, T. Figgemeier, S. Jung, C. Cacho, B. Büchner, J. Van Den Brink, C. M. Schneider, L. Plucinski, E. F. Schwier, K. Shimada, M. Richter, A. Isaeva, F. Reinert
    • Physical Review Letters 126, 176403 (2021)
    • DOI   Abstract  

      Using angle-resolved photoelectron spectroscopy (ARPES), we investigate the surface electronic structure of the magnetic van der Waals compounds MnBi4Te7 and MnBi6Te10, the n=1 and 2 members of a modular (Bi2Te3)n(MnBi2Te4) series, which have attracted recent interest as intrinsic magnetic topological insulators. Combining circular dichroic, spin-resolved and photon-energy-dependent ARPES measurements with calculations based on density functional theory, we unveil complex momentum-dependent orbital and spin textures in the surface electronic structure and disentangle topological from trivial surface bands. We find that the Dirac-cone dispersion of the topologial surface state is strongly perturbed by hybridization with valence-band states for Bi2Te3-terminated surfaces but remains preserved for MnBi2Te4-terminated surfaces. Our results firmly establish the topologically nontrivial nature of these magnetic van der Waals materials and indicate that the possibility of realizing a quantized anomalous Hall conductivity depends on surface termination. © 2021 American Physical Society.

      @ARTICLE{Vidal2021,
      author={Vidal, R.C. and Bentmann, H. and Facio, J.I. and Heider, T. and Kagerer, P. and Fornari, C.I. and Peixoto, T.R.F. and Figgemeier, T. and Jung, S. and Cacho, C. and Büchner, B. and Van Den Brink, J. and Schneider, C.M. and Plucinski, L. and Schwier, E.F. and Shimada, K. and Richter, M. and Isaeva, A. and Reinert, F.},
      title={Orbital Complexity in Intrinsic Magnetic Topological Insulators MnBi4Te7 and MnBi6Te10},
      journal={Physical Review Letters},
      year={2021},
      volume={126},
      number={17},
      doi={10.1103/PhysRevLett.126.176403},
      art_number={176403},
      note={cited By 21},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85105610972&doi=10.1103%2fPhysRevLett.126.176403&partnerID=40&md5=d160ee51f9df5334c14482f57e63eb0c},
      affiliation={Experimentelle Physik Vii, Universität Würzburg, Am Hubland, Würzburg, D-97074, Germany; Würzburg-Dresden Cluster of Excellence Ct.qmat, Germany; Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Helmholtzstr. 20, Dresden, D-01069, Germany; Peter Grünberg Institut, Forschungszentrum Jülich, Jara, Jülich, 52425, Germany; Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom; Department of Physics, Gyeongsang National University, Jinju, 52828, South Korea; Institut für Festkörper- und Materialphysik, Technische Universität Dresden, Dresden, D-01062, Germany; Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-0046, Japan; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, D-01062, Germany; Van der Waals - Zeeman Institute, Institute of Physics, University of Amsterdam, Amsterdam, 1098 XH, Netherlands},
      abstract={Using angle-resolved photoelectron spectroscopy (ARPES), we investigate the surface electronic structure of the magnetic van der Waals compounds MnBi4Te7 and MnBi6Te10, the n=1 and 2 members of a modular (Bi2Te3)n(MnBi2Te4) series, which have attracted recent interest as intrinsic magnetic topological insulators. Combining circular dichroic, spin-resolved and photon-energy-dependent ARPES measurements with calculations based on density functional theory, we unveil complex momentum-dependent orbital and spin textures in the surface electronic structure and disentangle topological from trivial surface bands. We find that the Dirac-cone dispersion of the topologial surface state is strongly perturbed by hybridization with valence-band states for Bi2Te3-terminated surfaces but remains preserved for MnBi2Te4-terminated surfaces. Our results firmly establish the topologically nontrivial nature of these magnetic van der Waals materials and indicate that the possibility of realizing a quantized anomalous Hall conductivity depends on surface termination. © 2021 American Physical Society.},
      keywords={Density functional theory; Electric insulators; Electronic structure; Magnetism; Manganese compounds; Photoelectron spectroscopy; Photons; Tellurium compounds; Textures; Topology; Van der Waals forces, Angle resolved photoelectron spectroscopy; Hall conductivity; Momentum-dependent; Photon energy; Surface electronic structures; Surface termination; Valence band state; Van der Waals compound, Bismuth compounds, angle resolved photoemission spectroscopy; article; circular dichroism; conductance; density functional theory},
      correspondence_address1={Bentmann, H.; Experimentelle Physik Vii, Am Hubland, Germany; email: Hendrik.Bentmann@physik.uni-wuerzburg.de},
      publisher={American Physical Society},
      issn={00319007},
      coden={PRLTA},
      pubmed_id={33988442},
      language={English},
      abbrev_source_title={Phys Rev Lett},
      document_type={Article},
      source={Scopus},
      }

  • Searching for Aquamelt Behavior among Silklike Biomimetics during Fibrillation under Flow
    • S. Donets, O. Guskova, J. -U. Sommer
    • Journal of Physical Chemistry B 125, 3238-3250 (2021)
    • DOI   Abstract  

      In this paper, we elucidate a generic mechanism behind strain-induced phase transition in aqueous solutions of silk-inspired biomimetics by atomistic molecular dynamics simulations. We show the results of modeling of homopeptides polyglycine Gly30 and polyalanine Ala30 and a heteropeptide (Gly-Ala-Gly-Ala-Gly-Ser)5, i.e., the simplest and yet relevant sequences that could mimic the behavior of natural silk under stress conditions. First, we analyze hydrophobicities of the sequences by calculating the Gibbs free energy of hydration and inspecting the interchain hydrogen bonding and hydration by water. Second, the force-extension profiles are scanned and compared with the results for poly(ethylene oxide), the synthetic polymer for which the aquamelt behavior has been proved recently. Additionally, the conformational transitions of oligopeptides from coiled to extended states are characterized by a generalized order parameter and by the dependence of the solvent-accessible surface area of the chains on applied stretching. Fibrillation itself is surveyed using both the two-dimensional interchain pair correlation function and the SAXS/WAXS patterns for the aggregates formed under stress. These are compared with experimental data found in the literature on fibril structure of silk composite materials doped with oligoalanine peptides. Our results show that tensile stress introduced into aqueous oligopeptide solutions facilitates interchain interactions. The oligopeptides display both a greater resistance to extension as compared to poly(ethylene oxide) and a reduced ability for hydrogen bonding of the stretched chains between oligomers and with water. Fiber formation is proved for all simulated objects, but the most structured one is made of a heteropeptide (Gly-Ala-Gly-Ala-Gly-Ser)5: For this sequence, we obtain the highest degree of the secondary structure motifs in the fiber. We conclude that this is the most promising candidate among considered sequences to find the aquamelt behavior in further experimental studies. © 2021 The Authors. Published by American Chemical Society.

      @ARTICLE{Donets20213238,
      author={Donets, S. and Guskova, O. and Sommer, J.-U.},
      title={Searching for Aquamelt Behavior among Silklike Biomimetics during Fibrillation under Flow},
      journal={Journal of Physical Chemistry B},
      year={2021},
      volume={125},
      number={12},
      pages={3238-3250},
      doi={10.1021/acs.jpcb.1c00647},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85103682088&doi=10.1021%2facs.jpcb.1c00647&partnerID=40&md5=5102ec0af2bcc8a39e3fdf90b4166bb5},
      affiliation={Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Institute of Theoretical Physics, Technische Universität Dresden, Zellescher Weg 17, Dresden, 01069, Germany},
      abstract={In this paper, we elucidate a generic mechanism behind strain-induced phase transition in aqueous solutions of silk-inspired biomimetics by atomistic molecular dynamics simulations. We show the results of modeling of homopeptides polyglycine Gly30 and polyalanine Ala30 and a heteropeptide (Gly-Ala-Gly-Ala-Gly-Ser)5, i.e., the simplest and yet relevant sequences that could mimic the behavior of natural silk under stress conditions. First, we analyze hydrophobicities of the sequences by calculating the Gibbs free energy of hydration and inspecting the interchain hydrogen bonding and hydration by water. Second, the force-extension profiles are scanned and compared with the results for poly(ethylene oxide), the synthetic polymer for which the aquamelt behavior has been proved recently. Additionally, the conformational transitions of oligopeptides from coiled to extended states are characterized by a generalized order parameter and by the dependence of the solvent-accessible surface area of the chains on applied stretching. Fibrillation itself is surveyed using both the two-dimensional interchain pair correlation function and the SAXS/WAXS patterns for the aggregates formed under stress. These are compared with experimental data found in the literature on fibril structure of silk composite materials doped with oligoalanine peptides. Our results show that tensile stress introduced into aqueous oligopeptide solutions facilitates interchain interactions. The oligopeptides display both a greater resistance to extension as compared to poly(ethylene oxide) and a reduced ability for hydrogen bonding of the stretched chains between oligomers and with water. Fiber formation is proved for all simulated objects, but the most structured one is made of a heteropeptide (Gly-Ala-Gly-Ala-Gly-Ser)5: For this sequence, we obtain the highest degree of the secondary structure motifs in the fiber. We conclude that this is the most promising candidate among considered sequences to find the aquamelt behavior in further experimental studies. © 2021 The Authors. Published by American Chemical Society.},
      keywords={Aggregates; Aliphatic compounds; Biomimetics; Composite structures; Ethylene; Free energy; Gibbs free energy; Hydration; Molecular dynamics; Peptides; Polyethylene oxides; Silk, Atomistic molecular dynamics simulations; Conformational transitions; Free energy of hydration; Interchain interactions; Pair correlation functions; Secondary structures; Solvent accessible surface areas; Synthetic polymers, Hydrogen bonds, silk, biomimetics; protein secondary structure; small angle scattering; X ray diffraction, Biomimetics; Protein Structure, Secondary; Scattering, Small Angle; Silk; X-Ray Diffraction},
      correspondence_address1={Donets, S.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: donets@ipfdd.de; Guskova, O.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: guskova@ipfdd.de; Sommer, J.-U.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: sommer@ipfdd.de},
      publisher={American Chemical Society},
      issn={15206106},
      coden={JPCBF},
      pubmed_id={33750140},
      language={English},
      abbrev_source_title={J Phys Chem B},
      document_type={Article},
      source={Scopus},
      }

  • Theoretical Insight into High-Efficiency Triple-Junction Tandem Solar Cells via the Band Engineering of Antimony Chalcogenides
    • Y. Cao, C. Liu, J. Jiang, X. Zhu, J. Zhou, J. Ni, J. Zhang, J. Pang, M. H. Rummeli, W. Zhou, H. Liu, G. Cuniberti
    • Solar RRL 5, 2000800 (2021)
    • DOI   Abstract  

      Antimony chalcogenides have become a family of promising photoelectric materials for high-efficiency solar cells. To date, single-junction solar cells based on individual antimony selenide or sulfide are dominant and show limited photoelectric conversion efficiency. Therefore, great gaps remain for the multiple junction solar cells. Herein, triple-junction antimony chalcogenides-based solar cells are designed and optimized with a theoretical efficiency of 32.98% through band engineering strategies with Sb2S3/Sb2(S0.7Se0.3)3/Sb2Se3 stacking. The optimum Se content of the mid-cell should be maintained low, i.e., 30% for achieving a low defect density in an absorber layer. Therefore, Sb2(S0.7Se0.3)3-based mid solar cells have contributed to elevate the external quantum efficiency in triple-junction devices by the full utilization of the solar spectrum. In a single-junction solar cell, the bandgap gradient is regulated through the Se content gradient along the depth profile of Sb2(S1−xSex)3. Besides, an increasing Se content profile provides an additional built-in electric field for boosting hole charge carrier collection. Thus, the high charge carrier generation rate leads to a 17.96% improvement in the conversion efficiency compared with a conventional cell. This work may pave the way to boost the conversion efficiency of antimony chalcogenides-based solar cells to their theoretical limits. © 2021 Wiley-VCH GmbH

      @ARTICLE{Cao2021,
      author={Cao, Y. and Liu, C. and Jiang, J. and Zhu, X. and Zhou, J. and Ni, J. and Zhang, J. and Pang, J. and Rummeli, M.H. and Zhou, W. and Liu, H. and Cuniberti, G.},
      title={Theoretical Insight into High-Efficiency Triple-Junction Tandem Solar Cells via the Band Engineering of Antimony Chalcogenides},
      journal={Solar RRL},
      year={2021},
      volume={5},
      number={4},
      doi={10.1002/solr.202000800},
      art_number={2000800},
      note={cited By 38},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85101602611&doi=10.1002%2fsolr.202000800&partnerID=40&md5=93616af3627d11f4dca5744b9520ddf4},
      affiliation={Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology, Ministry of Education (Northeast Electric Power University), Jilin, 132012, China; School of Electrical Engineering, Northeast Electric Power University, Jilin, 132012, China; School of Chemical Engineering, Northeast Electric Power University, Jilin, 132012, China; College of Electronic Information and Optical Engineering, Nankai University, Tianjin, 300350, China; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Jinan, 250022, China; College of Energy, Soochow Institute for Energy and Materials Innovations Soochow University, Suzhou, 215006, China; Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, 215006, China; Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie Sklodowskiej 34, Zabrze, 41-819, Poland; Institute for Complex Materials, IFW Dresden, 20 Helmholtz Strasse, Dresden, 01069, Germany; Institute of Environmental Technology, VŠB-Technical University of Ostrava, 17. Listopadu 15, Ostrava, 708 33, Czech Republic; State Key Laboratory of Crystal Materials, Center of Bio & Micro/Nano Functional Materials, Shandong University, 27 Shandanan Road, Jinan, 250100, China; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={Antimony chalcogenides have become a family of promising photoelectric materials for high-efficiency solar cells. To date, single-junction solar cells based on individual antimony selenide or sulfide are dominant and show limited photoelectric conversion efficiency. Therefore, great gaps remain for the multiple junction solar cells. Herein, triple-junction antimony chalcogenides-based solar cells are designed and optimized with a theoretical efficiency of 32.98% through band engineering strategies with Sb2S3/Sb2(S0.7Se0.3)3/Sb2Se3 stacking. The optimum Se content of the mid-cell should be maintained low, i.e., 30% for achieving a low defect density in an absorber layer. Therefore, Sb2(S0.7Se0.3)3-based mid solar cells have contributed to elevate the external quantum efficiency in triple-junction devices by the full utilization of the solar spectrum. In a single-junction solar cell, the bandgap gradient is regulated through the Se content gradient along the depth profile of Sb2(S1−xSex)3. Besides, an increasing Se content profile provides an additional built-in electric field for boosting hole charge carrier collection. Thus, the high charge carrier generation rate leads to a 17.96% improvement in the conversion efficiency compared with a conventional cell. This work may pave the way to boost the conversion efficiency of antimony chalcogenides-based solar cells to their theoretical limits. © 2021 Wiley-VCH GmbH},
      author_keywords={antimony chalcogenides; band engineering; quantum efficiencies; thin films; triple-junction tandem solar cells},
      keywords={Antimony compounds; Cell engineering; Chalcogenides; Charge carriers; Conversion efficiency; Efficiency; Electric fields; Photoelectricity; Selenium; Sulfide minerals; Sulfur compounds, Built-in electric fields; External quantum efficiency; High-efficiency solar cells; Low defect densities; Multiple junction solar cell; Photo-electric conversion efficiency; Single junction solar cells; Triple-junction tandem solar cells, Solar cells},
      correspondence_address1={Zhou, J.; School of Chemical Engineering, China; email: zhoujing@neepu.edu.cn; Pang, J.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, China; email: ifc_pangjb@ujn.edu.cn; Liu, H.; Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, China; email: hongliu@sdu.edu.cn; Liu, H.; State Key Laboratory of Crystal Materials, 27 Shandanan Road, China; email: hongliu@sdu.edu.cn; Cuniberti, G.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: gianaurelio.cuniberti@tu-dresden.de; Cuniberti, G.; Center for Advancing Electronics Dresden, Germany; email: gianaurelio.cuniberti@tu-dresden.de; Cuniberti, G.; Dresden Center for Computational Materials Science, Germany; email: gianaurelio.cuniberti@tu-dresden.de},
      publisher={John Wiley and Sons Inc},
      issn={2367198X},
      language={English},
      abbrev_source_title={Solar RRL},
      document_type={Article},
      source={Scopus},
      }

  • Multi-walled carbon nanotube dispersion methodologies in alkaline media and their influence on mechanical reinforcement of alkali-activated nanocomposites
    • M. Davoodabadi, M. Liebscher, S. Hampel, M. Sgarzi, A. B. Rezaie, D. Wolf, G. Cuniberti, V. Mechtcherine, J. Yang
    • Composites Part B: Engineering 209, 108559 (2021)
    • DOI   Abstract  

      The focus of present research is the establishment of a practical procedure for effective incorporation of multi-walled carbon nanotubes (MWCNTs) into alkali-activated materials (AAMs) with the aim of mechanical reinforcement. Investigated composite in this work was an alkali-activated matrix composed of fly ash (FA) and ground-granulated blast furnace-slag (GGBS) as solid aluminium-calcium-silicate precursors along with highly concentrated sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) as liquid alkaline activators. Na2SiO3, NaOH, and a combination of them were used for dispersion of MWCNTs. An anionic surfactant, naphthalene sulfonate (NS), and ultrasonication were applied to assist in the preparation of nanofluids. Optical microscopy, integral light transmission (ILT), and Fourier-transform infrared spectroscopy (FTIR) were performed to assess the colloidal behaviour of MWCNTs in the nanofluids. The possible dispersion mechanisms were furthermore hypothesised for each alkaline medium. Based on the outcomes, MWCNTs had the best dispersion performance in the Na2SiO3 based nanofluids. The relevant nanocomposites accordingly, in comparison to the other preparation methodologies in this research, indicated the highest improvements in flexural (65%) and compressive (30%) strengths as a consequence of 0.050 wt% MWCNT incorporation. Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) further clarified the reinforcement functionality and microstructure refinement of the MWCNTs dispersed in the Na2SiO3 based nanofluids. Altogether, this paper represents a broad insight concerning a better understanding of MWCNTs’ interactions in alkaline activators, i.e. dispersion media, and AAMs, i.e. host matrices, to obtain the highest possible mechanical and microstructural performance of reinforced nanocomposites. © 2021 Elsevier Ltd

      @ARTICLE{Davoodabadi2021,
      author={Davoodabadi, M. and Liebscher, M. and Hampel, S. and Sgarzi, M. and Rezaie, A.B. and Wolf, D. and Cuniberti, G. and Mechtcherine, V. and Yang, J.},
      title={Multi-walled carbon nanotube dispersion methodologies in alkaline media and their influence on mechanical reinforcement of alkali-activated nanocomposites},
      journal={Composites Part B: Engineering},
      year={2021},
      volume={209},
      doi={10.1016/j.compositesb.2020.108559},
      art_number={108559},
      note={cited By 8},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85100019051&doi=10.1016%2fj.compositesb.2020.108559&partnerID=40&md5=815c8fb302e5a298cab412dbfeb67097},
      affiliation={Department of Civil Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China; Institute of Construction Materials, Faculty of Civil Engineering, TU Dresden, Dresden, 01069, Germany; Leibniz Institute for Solid State and Materials Research, Dresden, 01069, Germany; Institute for Materials Science and Max Bergmann Centre of Biomaterials, TU Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden (CfAED), TU Dresden, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01069, Germany},
      abstract={The focus of present research is the establishment of a practical procedure for effective incorporation of multi-walled carbon nanotubes (MWCNTs) into alkali-activated materials (AAMs) with the aim of mechanical reinforcement. Investigated composite in this work was an alkali-activated matrix composed of fly ash (FA) and ground-granulated blast furnace-slag (GGBS) as solid aluminium-calcium-silicate precursors along with highly concentrated sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) as liquid alkaline activators. Na2SiO3, NaOH, and a combination of them were used for dispersion of MWCNTs. An anionic surfactant, naphthalene sulfonate (NS), and ultrasonication were applied to assist in the preparation of nanofluids. Optical microscopy, integral light transmission (ILT), and Fourier-transform infrared spectroscopy (FTIR) were performed to assess the colloidal behaviour of MWCNTs in the nanofluids. The possible dispersion mechanisms were furthermore hypothesised for each alkaline medium. Based on the outcomes, MWCNTs had the best dispersion performance in the Na2SiO3 based nanofluids. The relevant nanocomposites accordingly, in comparison to the other preparation methodologies in this research, indicated the highest improvements in flexural (65%) and compressive (30%) strengths as a consequence of 0.050 wt% MWCNT incorporation. Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) further clarified the reinforcement functionality and microstructure refinement of the MWCNTs dispersed in the Na2SiO3 based nanofluids. Altogether, this paper represents a broad insight concerning a better understanding of MWCNTs’ interactions in alkaline activators, i.e. dispersion media, and AAMs, i.e. host matrices, to obtain the highest possible mechanical and microstructural performance of reinforced nanocomposites. © 2021 Elsevier Ltd},
      author_keywords={Alkali-activated materials; Carbon nanotubes; Colloidal interactions; Mechanical properties; Microstructure; Nanocomposites; Nanofluids},
      keywords={Aluminum compounds; Anionic surfactants; Blast furnaces; Calcium silicate; Fly ash; Fourier transform infrared spectroscopy; Light transmission; Nanocomposites; Nanofluidics; Nanotubes; Naphthalene; Reinforcement; Scanning electron microscopy; Silicates; Silicon; Slags; Sodium hydroxide; Sols, Dispersion mechanisms; Dispersion performance; Ground granulated blast furnace slag; Mechanical reinforcement; Mercury intrusion porosimetry; Microstructure refinement; Naphthalene sulfonates; Reinforced nanocomposite, Multiwalled carbon nanotubes (MWCN)},
      correspondence_address1={Liebscher, M.; Institute of Construction Materials, Germany; email: marco.liebscher@tu-dresden.de; Hampel, S.; Leibniz Institute for Solid State and Materials ResearchGermany; email: S.Hampel@ifw-dresden.de; Cuniberti, G.; Institute for Materials Science and Max Bergmann Centre of Biomaterials, Germany; email: gianaurelio.cuniberti@tu-dresden.de; Yang, J.; Department of Civil Engineering, China; email: j.yang.1@sjtu.edu.cn},
      publisher={Elsevier Ltd},
      issn={13598368},
      coden={CPBEF},
      language={English},
      abbrev_source_title={Compos Part B: Eng},
      document_type={Article},
      source={Scopus},
      }

  • Pressure-induced structural transition and antiferromagnetism in elemental terbium
    • D. P. Kozlenko, V. Y. Yushankhai, R. Hayn, M. Richter, N. O. Golosova, S. E. Kichanov, E. V. Lukin, B. N. Savenko
    • Physical Review Materials 5, 034402 (2021)
    • DOI   Abstract  

      Structural and magnetic properties of rare-earth Tb metal have been studied by means of neutron powder diffraction at pressures up to 9 GPa in the temperature range 7-290 K. A structural phase transition from the initial hexagonal close-packed (hcp) to the Sm-type rhombohedral phase develops gradually at high pressures above 4 GPa. The initial ferromagnetic state in the hcp phase is suppressed and an antiferromagnetic state is developed in the pressure-induced phase. In the Sm-type structure and the temperature range below TMO=110K (at 9 GPa) down to 50 K, long-range order of Tb magnetic moments located in the layers resembling hexagonal close-packing type is formed with a propagation vector kAF1=(0012), while the layers resembling cubic close-packing type remain disordered. This partial disorder disappears at temperatures below 50 K when magnetic order, including the moments in the latter layers, develops with a propagation vector kAF2=(12012). The relative stability of the hcp and Sm-type structures under pressure was examined by density functional theory calculations, providing significant support to the experimental findings. The calculated bulk moduli of the hcp and Sm-type phases are close to the experimentally determined ones and the estimate P0≈4GPa obtained for the equilibrium transition pressure is close to the onset pressure found in real material. The volume collapse at the hcp to Sm-type transition was evaluated to amount to 0.4Å3 per atom. © 2021 American Physical Society.

      @ARTICLE{Kozlenko2021,
      author={Kozlenko, D.P. and Yushankhai, V.Y. and Hayn, R. and Richter, M. and Golosova, N.O. and Kichanov, S.E. and Lukin, E.V. and Savenko, B.N.},
      title={Pressure-induced structural transition and antiferromagnetism in elemental terbium},
      journal={Physical Review Materials},
      year={2021},
      volume={5},
      number={3},
      doi={10.1103/PhysRevMaterials.5.034402},
      art_number={034402},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85104256814&doi=10.1103%2fPhysRevMaterials.5.034402&partnerID=40&md5=a7a9ee1f101d77ea5cf46a7939b58a5e},
      affiliation={Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, 141980, Russian Federation; Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, 141980, Russian Federation; Dubna State University, Dubna, 141982, Russian Federation; Aix-Marseille Université, CNRS, IM2NP-UMR7334, Marseille Cedex 20, 13397, France; Leibniz IFW Dresden, Helmholtzstraße 20, Dresden, D-01069, Germany; Max-Planck Institut für Physik Komplexer Systeme, Dresden, D-01187, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, D-01062, Germany},
      abstract={Structural and magnetic properties of rare-earth Tb metal have been studied by means of neutron powder diffraction at pressures up to 9 GPa in the temperature range 7-290 K. A structural phase transition from the initial hexagonal close-packed (hcp) to the Sm-type rhombohedral phase develops gradually at high pressures above 4 GPa. The initial ferromagnetic state in the hcp phase is suppressed and an antiferromagnetic state is developed in the pressure-induced phase. In the Sm-type structure and the temperature range below TMO=110K (at 9 GPa) down to 50 K, long-range order of Tb magnetic moments located in the layers resembling hexagonal close-packing type is formed with a propagation vector kAF1=(0012), while the layers resembling cubic close-packing type remain disordered. This partial disorder disappears at temperatures below 50 K when magnetic order, including the moments in the latter layers, develops with a propagation vector kAF2=(12012). The relative stability of the hcp and Sm-type structures under pressure was examined by density functional theory calculations, providing significant support to the experimental findings. The calculated bulk moduli of the hcp and Sm-type phases are close to the experimentally determined ones and the estimate P0≈4GPa obtained for the equilibrium transition pressure is close to the onset pressure found in real material. The volume collapse at the hcp to Sm-type transition was evaluated to amount to 0.4Å3 per atom. © 2021 American Physical Society.},
      keywords={Antiferromagnetism; Magnetic moments; Rare earths; Terbium, Antiferromagnetic state; Equilibrium transitions; Hexagonal close packed; Hexagonal close packing; Pressure-induced phase; Pressure-induced structural transitions; Structural and magnetic properties; Structural phase transition, Density functional theory},
      correspondence_address1={Kozlenko, D.P.; Frank Laboratory of Neutron Physics, Russian Federation; email: denk@nf.jinr.ru},
      publisher={American Physical Society},
      issn={24759953},
      language={English},
      abbrev_source_title={Physic. Rev. Mat.},
      document_type={Article},
      source={Scopus},
      }

  • Nanoscale Phononic Analog of the Ranque-Hilsch Vortex Tube
    • L. Medrano Sandonas, Á. Rodríguez Méndez, R. Gutierrez, G. Cuniberti, V. Mujica
    • Physical Review Applied 15, 034008 (2021)
    • DOI   Abstract  

      Thermal management is a current global challenge that must be addressed exhaustively. We propose the design of a nanoscale phononic analog of the Ranque-Hilsch vortex tube in which heat flowing at a given temperature is split into two different streams going to the two ends of the device, inducing a temperature asymmetry. Our nanoscale prototype consists of two carbon nanotubes (capped and open) connected by molecular chains. The results show that the structural asymmetry in the contact regions is the key factor for producing the flux asymmetry and, hence, the induced temperature-bias effect. The effect can be controlled by tuning the thermal-equilibration temperature, the number of chains, and the chain length. Deposition on a substrate adds another variable to the manipulation of the flux asymmetry but the effect vanishes at very large substrate temperatures. Our study yields insights into the thermal management in nanoscale materials, especially the crucial issue of whether the thermal asymmetry can survive phonon scattering over relatively long distances, and thus provides a starting point for the design of a nanoscale phononic analog of the Ranque-Hilsch vortex tube. © 2021 American Physical Society.

      @ARTICLE{MedranoSandonas2021,
      author={Medrano Sandonas, L. and Rodríguez Méndez, Á. and Gutierrez, R. and Cuniberti, G. and Mujica, V.},
      title={Nanoscale Phononic Analog of the Ranque-Hilsch Vortex Tube},
      journal={Physical Review Applied},
      year={2021},
      volume={15},
      number={3},
      doi={10.1103/PhysRevApplied.15.034008},
      art_number={034008},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85103436975&doi=10.1103%2fPhysRevApplied.15.034008&partnerID=40&md5=7dc6e35c0c752d2389bc69bfeec8480f},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, Tu Dresden, Dresden, 01062, Germany; Department of Physics and Materials Science, University of Luxembourg, Luxembourg, L-1511, Luxembourg; Center for Advancing Electronics Dresden, Tu Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Tu Dresden, Dresden, 01062, Germany; School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, United States; Kimika Fakultatea, Euskal Herriko Unibertsitatea and Donostia International Physics Center (DIPC), P. K. 1072, Donostia, Euskadi, 20080, Spain},
      abstract={Thermal management is a current global challenge that must be addressed exhaustively. We propose the design of a nanoscale phononic analog of the Ranque-Hilsch vortex tube in which heat flowing at a given temperature is split into two different streams going to the two ends of the device, inducing a temperature asymmetry. Our nanoscale prototype consists of two carbon nanotubes (capped and open) connected by molecular chains. The results show that the structural asymmetry in the contact regions is the key factor for producing the flux asymmetry and, hence, the induced temperature-bias effect. The effect can be controlled by tuning the thermal-equilibration temperature, the number of chains, and the chain length. Deposition on a substrate adds another variable to the manipulation of the flux asymmetry but the effect vanishes at very large substrate temperatures. Our study yields insights into the thermal management in nanoscale materials, especially the crucial issue of whether the thermal asymmetry can survive phonon scattering over relatively long distances, and thus provides a starting point for the design of a nanoscale phononic analog of the Ranque-Hilsch vortex tube. © 2021 American Physical Society.},
      keywords={Nanotechnology; Temperature control, Global challenges; Induced temperature; Nano-scale materials; Ranque-Hilsch vortex tube; Structural asymmetry; Substrate temperature; Thermal asymmetry; Thermal equilibrations, Vortex flow},
      correspondence_address1={Medrano Sandonas, L.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: leonardo.medrano@uni.lu; Medrano Sandonas, L.; Department of Physics and Materials Science, Luxembourg; email: leonardo.medrano@uni.lu},
      publisher={American Physical Society},
      issn={23317019},
      language={English},
      abbrev_source_title={Phys. Rev. Appl.},
      document_type={Article},
      source={Scopus},
      }

  • Highly sensitive room temperature ammonia gas sensor using pristine graphene: The role of biocompatible stabilizer
    • S. Huang, L. A. Panes-Ruiz, A. Croy, M. Löffler, V. Khavrus, V. Bezugly, G. Cuniberti
    • Carbon 173, 262-270 (2021)
    • DOI   Abstract  

      Graphene has attracted extraordinary attention for gas sensing due to its large specific surface area as well as its high charge carrier mobility. Nonetheless, in most cases, graphene derivatives, such as reduced graphene oxide (rGO), were employed as sensing elements instead of pristine graphene. In this contribution, pristine graphene noncovalently functionalized by a biocompatible stabilizer (flavin monocleotide sodium salt, FMNS) was produced for the application as NH3 sensing materials in a chemiresistor type gas sensor. Detailed characterizations indicate that the graphene flakes exhibit good structural quality with few defects. The optimized ammonia sensors demonstrate outstanding performance: ultralow limit-of-detection (1.6 ppm), excellent sensitivity (2.8%, 10 ppm; 18.5%, 1000 ppm), reproducibility, reversibility, low power consumption (work temperature, 25 °C) as well as low cost. Additionally, the roles of FMNS from graphene preparation to NH3 sensing are elucidated via all-atom molecular dynamics simulations: (1) stabilizer for the graphene dispersion, (2) p-type dopant for graphene-based sensing element, and (3) active adsorption sites for NH3 gas sensing. This contribution provides an efficient strategy to design highly sensitive pristine graphene-based NH3 gas sensors utilizing FMNS-like molecules, involving a facile and environmentally friendly process, biocompatible materials, low cost equipment, and scale-up capability. © 2020 Elsevier Ltd

      @ARTICLE{Huang2021262,
      author={Huang, S. and Panes-Ruiz, L.A. and Croy, A. and Löffler, M. and Khavrus, V. and Bezugly, V. and Cuniberti, G.},
      title={Highly sensitive room temperature ammonia gas sensor using pristine graphene: The role of biocompatible stabilizer},
      journal={Carbon},
      year={2021},
      volume={173},
      pages={262-270},
      doi={10.1016/j.carbon.2020.11.001},
      note={cited By 19},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85096354195&doi=10.1016%2fj.carbon.2020.11.001&partnerID=40&md5=de149cf81d3b3d020bee77e038e5b41f},
      affiliation={Institute for Materials Science and Max Bergmann Center for Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Nanoanalysis, Center for Advancing Electronics Dresden (CfAED), TU Dresden, Dresden, 01187, Germany; Life Science Inkubator Sachsen GmbH & Co. KG, Tatzberg 47, Dresden, 01307, Germany; Center for Advancing Electronics Dresden (cfAED), TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Graphene has attracted extraordinary attention for gas sensing due to its large specific surface area as well as its high charge carrier mobility. Nonetheless, in most cases, graphene derivatives, such as reduced graphene oxide (rGO), were employed as sensing elements instead of pristine graphene. In this contribution, pristine graphene noncovalently functionalized by a biocompatible stabilizer (flavin monocleotide sodium salt, FMNS) was produced for the application as NH3 sensing materials in a chemiresistor type gas sensor. Detailed characterizations indicate that the graphene flakes exhibit good structural quality with few defects. The optimized ammonia sensors demonstrate outstanding performance: ultralow limit-of-detection (1.6 ppm), excellent sensitivity (2.8%, 10 ppm; 18.5%, 1000 ppm), reproducibility, reversibility, low power consumption (work temperature, 25 °C) as well as low cost. Additionally, the roles of FMNS from graphene preparation to NH3 sensing are elucidated via all-atom molecular dynamics simulations: (1) stabilizer for the graphene dispersion, (2) p-type dopant for graphene-based sensing element, and (3) active adsorption sites for NH3 gas sensing. This contribution provides an efficient strategy to design highly sensitive pristine graphene-based NH3 gas sensors utilizing FMNS-like molecules, involving a facile and environmentally friendly process, biocompatible materials, low cost equipment, and scale-up capability. © 2020 Elsevier Ltd},
      author_keywords={Ammonia gas sensor; Biocompatibility; Flavin mononucleotide sodium; Graphene; Molecular dynamic simulations},
      keywords={Ammonia; Biocompatibility; Chemical detection; Chemical sensors; Costs; Gas detectors; Gas sensing electrodes; Gases; Hall mobility; Hole mobility; Molecular dynamics; Reduced Graphene Oxide, Ammonia gas sensors; Environmentally friendly process; Graphene dispersions; Large specific surface areas; Low-power consumption; Molecular dynamics simulations; Reduced graphene oxides (RGO); Structural qualities, Graphene},
      correspondence_address1={Croy, A.; Institute for Materials Science and Max Bergmann Center for Biomaterials, Germany; email: alexander.croy@tu-dresden.de; Bezugly, V.; Institute for Materials Science and Max Bergmann Center for Biomaterials, Germany; email: viktor.bezugly@tu-dresden.de; Cuniberti, G.; Institute for Materials Science and Max Bergmann Center for Biomaterials, Germany; email: gianaurelio.cuniberti@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={00086223},
      coden={CRBNA},
      language={English},
      abbrev_source_title={Carbon},
      document_type={Article},
      source={Scopus},
      }

  • Investigating a Combined Stochastic Nucleation and Molecular Dynamics-Based Equilibration Approach for Constructing Large-Scale Polycrystalline Films
    • K. S. Schellhammer, G. Cuniberti, F. Ortmann
    • Journal of Chemical Theory and Computation 17, 1266-1275 (2021)
    • DOI   Abstract  

      The morphology of small-molecule organic semiconducting materials can vary from single crystals via polycrystalline films with varying grain sizes to amorphous structures, depending on the process conditions. This structural variety affects the electronic properties and, thus, the performance of organic electronic devices. A nucleation-equilibration approach is investigated, whose focus is on the construction of morphologies with controlled variations in the average grain size. Its computational requirements are low because nucleation is purely based on geometrical considerations, thus allowing the construction of model systems of experimentally relevant sizes. Its application is demonstrated for C60 and pentacene by generating single-component films that vary from amorphous to crystalline structures. It is further generalized to two-component films and applied to C60: Pentacene blends as well as dilute n-doped C60 structures. When combined with electronic structure calculations in the future, the nucleation-equilibration approach can offer insights into the impact of polycrystallinity on electronic and charge-transport properties in the absence of any knowledge about the growth mechanism and for a broad set of systems. © 2021 American Chemical Society. All rights reserved.

      @ARTICLE{Schellhammer20211266,
      author={Schellhammer, K.S. and Cuniberti, G. and Ortmann, F.},
      title={Investigating a Combined Stochastic Nucleation and Molecular Dynamics-Based Equilibration Approach for Constructing Large-Scale Polycrystalline Films},
      journal={Journal of Chemical Theory and Computation},
      year={2021},
      volume={17},
      number={2},
      pages={1266-1275},
      doi={10.1021/acs.jctc.0c01196},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85100038120&doi=10.1021%2facs.jctc.0c01196&partnerID=40&md5=5f3d106a1df883af1e0973956e04daea},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01062, Germany; Department of Chemistry, Technische Universität München, Lichtenbergstr. 4, Garching, 85748, Germany},
      abstract={The morphology of small-molecule organic semiconducting materials can vary from single crystals via polycrystalline films with varying grain sizes to amorphous structures, depending on the process conditions. This structural variety affects the electronic properties and, thus, the performance of organic electronic devices. A nucleation-equilibration approach is investigated, whose focus is on the construction of morphologies with controlled variations in the average grain size. Its computational requirements are low because nucleation is purely based on geometrical considerations, thus allowing the construction of model systems of experimentally relevant sizes. Its application is demonstrated for C60 and pentacene by generating single-component films that vary from amorphous to crystalline structures. It is further generalized to two-component films and applied to C60: Pentacene blends as well as dilute n-doped C60 structures. When combined with electronic structure calculations in the future, the nucleation-equilibration approach can offer insights into the impact of polycrystallinity on electronic and charge-transport properties in the absence of any knowledge about the growth mechanism and for a broad set of systems. © 2021 American Chemical Society. All rights reserved.},
      correspondence_address1={Ortmann, F.; Dresden Center for Computational Materials Science, Germany; email: frank.ortmann@tum.de},
      publisher={American Chemical Society},
      issn={15499618},
      coden={JCTCC},
      pubmed_id={33434021},
      language={English},
      abbrev_source_title={J. Chem. Theory Comput.},
      document_type={Article},
      source={Scopus},
      }

  • Surface-Phonon-Induced Rotational Dissipation for Nanoscale Solid-State Gears
    • H. -H. Lin, A. Croy, R. Gutierrez, G. Cuniberti
    • Physical Review Applied 15, 024053 (2021)
    • DOI   Abstract  

      Compared to nanoscale friction of translational motion, the mechanisms of rotational friction have received less attention. Such motion becomes an important issue for the miniaturization of mechanical machinery that often involves rotating gears. In this study, molecular-dynamics simulations are performed to explore rotational friction for solid-state gears rotating on top of different substrates. In each case, viscous damping of the rotational motion is observed and found to be induced by the pure van der Waals interaction between the gear and the substrate. The influence of different gear sizes and various substrate materials is investigated. Furthermore, the rigidities of the gear and the substrate are found to give rise to different dissipation channels. Finally, it is shown that the dominant contribution to the dissipation is related to the excitation of low-frequency surface phonons in the substrate. © 2021 American Physical Society.

      @ARTICLE{Lin2021,
      author={Lin, H.-H. and Croy, A. and Gutierrez, R. and Cuniberti, G.},
      title={Surface-Phonon-Induced Rotational Dissipation for Nanoscale Solid-State Gears},
      journal={Physical Review Applied},
      year={2021},
      volume={15},
      number={2},
      doi={10.1103/PhysRevApplied.15.024053},
      art_number={024053},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85102407399&doi=10.1103%2fPhysRevApplied.15.024053&partnerID=40&md5=81615e817c02d1610197452435b65dfe},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01069, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={Compared to nanoscale friction of translational motion, the mechanisms of rotational friction have received less attention. Such motion becomes an important issue for the miniaturization of mechanical machinery that often involves rotating gears. In this study, molecular-dynamics simulations are performed to explore rotational friction for solid-state gears rotating on top of different substrates. In each case, viscous damping of the rotational motion is observed and found to be induced by the pure van der Waals interaction between the gear and the substrate. The influence of different gear sizes and various substrate materials is investigated. Furthermore, the rigidities of the gear and the substrate are found to give rise to different dissipation channels. Finally, it is shown that the dominant contribution to the dissipation is related to the excitation of low-frequency surface phonons in the substrate. © 2021 American Physical Society.},
      keywords={Friction; Machinery; Molecular dynamics; Nanotechnology; Phonons; Van der Waals forces, Different substrates; Dominant contributions; Molecular dynamics simulations; Nanoscale friction; Rotational friction; Translational motions; Van Der Waals interactions; Various substrates, Substrates},
      publisher={American Physical Society},
      issn={23317019},
      language={English},
      abbrev_source_title={Phys. Rev. Appl.},
      document_type={Article},
      source={Scopus},
      }

  • Predicting the bulk modulus of single-layer covalent organic frameworks with square-lattice topology from molecular building-block properties
    • A. Raptakis, A. Dianat, A. Croy, G. Cuniberti
    • Nanoscale 13, 1077-1085 (2021)
    • DOI   Abstract  

      Two-dimensional Covalent Organic Frameworks (2D COFs) have attracted a lot of interest because of their potential for a broad range of applications. Different combinations of their molecular building blocks can lead to new materials with different physical and chemical properties. In this study, the elasticity of different single-layer tetrabenzoporphyrin (H2-TBPor) and phthalocyanine (H2-Pc) based 2D COFs is numerically investigated using a density-functional based tight-binding approach. Specifically, we calculate the 2D bulk modulus and the equivalent spring constants of the respective molecular building-blocks. Using a spring network model we are able to predict the 2D bulk modulus based on the properties of the isolated molecules. This provides a path to optimize elastic properties of 2D COFs. This journal is © The Royal Society of Chemistry.

      @ARTICLE{Raptakis20211077,
      author={Raptakis, A. and Dianat, A. and Croy, A. and Cuniberti, G.},
      title={Predicting the bulk modulus of single-layer covalent organic frameworks with square-lattice topology from molecular building-block properties},
      journal={Nanoscale},
      year={2021},
      volume={13},
      number={2},
      pages={1077-1085},
      doi={10.1039/d0nr07666j},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85099792497&doi=10.1039%2fd0nr07666j&partnerID=40&md5=28767b6e0d30412257f7be65866af2bc},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Two-dimensional Covalent Organic Frameworks (2D COFs) have attracted a lot of interest because of their potential for a broad range of applications. Different combinations of their molecular building blocks can lead to new materials with different physical and chemical properties. In this study, the elasticity of different single-layer tetrabenzoporphyrin (H2-TBPor) and phthalocyanine (H2-Pc) based 2D COFs is numerically investigated using a density-functional based tight-binding approach. Specifically, we calculate the 2D bulk modulus and the equivalent spring constants of the respective molecular building-blocks. Using a spring network model we are able to predict the 2D bulk modulus based on the properties of the isolated molecules. This provides a path to optimize elastic properties of 2D COFs. This journal is © The Royal Society of Chemistry.},
      keywords={Electric network topology; Springs (components), Covalent organic frameworks; Density functional based tight bindings; Equivalent springs; Isolated molecules; Molecular building blocks; Physical and chemical properties; Spring network model; Tetrabenzoporphyrins, Elastic moduli},
      correspondence_address1={Croy, A.; Institute for Materials Science, Germany; email: alexander.croy@tu-dresden.de},
      publisher={Royal Society of Chemistry},
      issn={20403364},
      pubmed_id={33393581},
      language={English},
      abbrev_source_title={Nanoscale},
      document_type={Article},
      source={Scopus},
      }

  • Magneto-mechanical coupling in magneto-active elastomers
    • P. Metsch, D. Romeis, K. A. Kalina, A. Raßloff, M. Saphiannikova, M. Kästner
    • Materials 14, 1-27 , 434 (2021)
    • DOI   Abstract  

      In the present work, the magneto-mechanical coupling in magneto-active elastomers is investigated from two different modeling perspectives: a micro-continuum and a particle–interaction approach. Since both strategies differ significantly in their basic assumptions and the resolution of the problem under investigation, they are introduced in a concise manner and their capabilities are illustrated by means of representative examples. To motivate the application of these strategies within a hybrid multiscale framework for magneto-active elastomers, their interchangeability is then examined in a systematic comparison of the model predictions with regard to the magneto-deformation of chain-like helical structures in an elastomer surrounding. The presented results show a remarkable agreement of both modeling approaches and help to provide an improved understanding of the interactions in magneto-active elastomers with chain-like microstructures. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

      @ARTICLE{Metsch20211,
      author={Metsch, P. and Romeis, D. and Kalina, K.A. and Raßloff, A. and Saphiannikova, M. and Kästner, M.},
      title={Magneto-mechanical coupling in magneto-active elastomers},
      journal={Materials},
      year={2021},
      volume={14},
      number={2},
      pages={1-27},
      doi={10.3390/ma14020434},
      art_number={434},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85099543750&doi=10.3390%2fma14020434&partnerID=40&md5=bfad931a9d4d3ff37f4ac5c5e42885a9},
      affiliation={Institute of Solid Mechanics, Technische Universität Dresden, Dresden, 01062, Germany; Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={In the present work, the magneto-mechanical coupling in magneto-active elastomers is investigated from two different modeling perspectives: a micro-continuum and a particle–interaction approach. Since both strategies differ significantly in their basic assumptions and the resolution of the problem under investigation, they are introduced in a concise manner and their capabilities are illustrated by means of representative examples. To motivate the application of these strategies within a hybrid multiscale framework for magneto-active elastomers, their interchangeability is then examined in a systematic comparison of the model predictions with regard to the magneto-deformation of chain-like helical structures in an elastomer surrounding. The presented results show a remarkable agreement of both modeling approaches and help to provide an improved understanding of the interactions in magneto-active elastomers with chain-like microstructures. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.},
      author_keywords={Magneto-active elastomers; Magneto-deformation; Magneto-mechanical coupling; Magneto-striction},
      keywords={Couplings; Plastics, A-particles; Chain-like; Helical structures; Magnetomechanical couplings; Model approach; Model prediction; Multi-scale frameworks, Elastomers},
      correspondence_address1={Romeis, D.; Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, Germany; email: romeis@ipfdd.de; Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de; Kästner, M.; Dresden Center for Computational Materials Science (DCMS), Germany; email: markus.kaestner@tu-dresden.de},
      publisher={MDPI AG},
      issn={19961944},
      language={English},
      abbrev_source_title={Mater.},
      document_type={Article},
      source={Scopus},
      }

  • Determination of Cleavage Energy and Efficient Nanostructuring of Layered Materials by Atomic Force Microscopy
    • B. Rasche, J. Brunner, T. Schramm, M. P. Ghimire, U. Nitzsche, B. Büchner, R. Giraud, M. Richter, J. Dufouleur
    • Nano Letters (2021)
    • DOI   Abstract  

      A method is presented to use atomic force microscopy to measure the cleavage energy of van der Waals materials and similar quasi-two-dimensional materials. The cleavage energy of graphite is measured to be 0.36 J/m2, in good agreement with literature data. The same method yields a cleavage energy of 0.6 J/m2 for MoS2 as a representative of the dichalcogenides. In the case of the weak topological insulator Bi14Rh3I9 no cleavage energy is obtained, although cleavage is successful with an adapted approach. The cleavage energies of these materials are evaluated by means of density-functional calculations and literature data. This further validates the presented method and sets an upper limit of about 0.7 J/m2 to the cleavage energy that can be measured by the present setup. In addition, this method can be used as a tool for manipulating exfoliated flakes, prior to or after contacting, which may open a new route for the fabrication of nanostructures. © 2022 American Chemical Society.

      @ARTICLE{Rasche2021,
      author={Rasche, B. and Brunner, J. and Schramm, T. and Ghimire, M.P. and Nitzsche, U. and Büchner, B. and Giraud, R. and Richter, M. and Dufouleur, J.},
      title={Determination of Cleavage Energy and Efficient Nanostructuring of Layered Materials by Atomic Force Microscopy},
      journal={Nano Letters},
      year={2021},
      doi={10.1021/acs.nanolett.1c04868},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85128599011&doi=10.1021%2facs.nanolett.1c04868&partnerID=40&md5=cd860988609965ccf45285c3ad09850b},
      affiliation={Department Of Chemistry, University Of Cologne, Cologne, 50939, Germany; Leibniz Ifw Dresden, Helmholtzstrasse 20, Dresden, D-01069, Germany; Central Department Of Physics, Tribhuvan University, Kirtipur, Kathmandu, 44613, Nepal; Center For Transport And Devices, Tu Dresden, Dresden, D-01062, Germany; Department Of Physics, Tu Dresden, Dresden, D-01062, Germany; Dresden Center For Computational Materials Science (DCMS), Tu Dresden, Dresden, D-01062, Germany; Université Grenoble Alpes, Cnrs, Cea, Grenoble-INP, Spintec, Grenoble, F-38000, France},
      abstract={A method is presented to use atomic force microscopy to measure the cleavage energy of van der Waals materials and similar quasi-two-dimensional materials. The cleavage energy of graphite is measured to be 0.36 J/m2, in good agreement with literature data. The same method yields a cleavage energy of 0.6 J/m2 for MoS2 as a representative of the dichalcogenides. In the case of the weak topological insulator Bi14Rh3I9 no cleavage energy is obtained, although cleavage is successful with an adapted approach. The cleavage energies of these materials are evaluated by means of density-functional calculations and literature data. This further validates the presented method and sets an upper limit of about 0.7 J/m2 to the cleavage energy that can be measured by the present setup. In addition, this method can be used as a tool for manipulating exfoliated flakes, prior to or after contacting, which may open a new route for the fabrication of nanostructures. © 2022 American Chemical Society.},
      author_keywords={atomic force microscopy; cleavage energy; nanostructuring; two-dimensional materials; van der Waals materials},
      keywords={Atomic force microscopy; Bismuth compounds; Electric insulators; Iodine compounds; Layered semiconductors; Molybdenum compounds; Rhodium compounds; Sulfur compounds, Atomic-force-microscopy; Cleavage energy; Dichalcogenides; Energy; Layered material; Literature data; Nano-structuring; Two-dimensional materials; Van der Waal; Van der waal material, Van der Waals forces},
      correspondence_address1={Rasche, B.; Department Of Chemistry, Germany; email: bertold.rasche@uni-koeln.de; Dufouleur, J.; Leibniz Ifw Dresden, Helmholtzstrasse 20, Germany; email: j.dufouleur@ifw-dresden.de},
      publisher={American Chemical Society},
      issn={15306984},
      coden={NALEF},
      pubmed_id={35427144},
      language={English},
      abbrev_source_title={Nano Lett.},
      document_type={Article},
      source={Scopus},
      }

  • Erratum to “Phase-field modeling of crack branching and deflection in heterogeneous media” [Eng. Fract. Mech. 232 (2020) 107004] (Engineering Fracture Mechanics (2020) 232, (S0013794419315474), (10.1016/j.engfracmech.2020.107004))
    • A. C. Hansen-Dörr, F. Dammaß, R. de Borst, M. Kästner
    • Engineering Fracture Mechanics 241, 107449 (2021)
    • DOI   Abstract  

      In Section 2.7, the solution of heterogeneous, one-dimensional phase-field profiles with the intent to improve previous analytical correction approaches was brought into consideration in a personal communication by Keita Yoshioka, Helmholtz Centre for Environmental Research. © 2020

      @ARTICLE{Hansen-Dörr2021,
      author={Hansen-Dörr, A.C. and Dammaß, F. and de Borst, R. and Kästner, M.},
      title={Erratum to “Phase-field modeling of crack branching and deflection in heterogeneous media” [Eng. Fract. Mech. 232 (2020) 107004] (Engineering Fracture Mechanics (2020) 232, (S0013794419315474), (10.1016/j.engfracmech.2020.107004))},
      journal={Engineering Fracture Mechanics},
      year={2021},
      volume={241},
      doi={10.1016/j.engfracmech.2020.107449},
      art_number={107449},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85097738647&doi=10.1016%2fj.engfracmech.2020.107449&partnerID=40&md5=a5969e1892eb918aaef6ad1877149234},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, 01062, Germany; University of Sheffield, Department of Civil and Structural Engineering, Mappin Street, Sir Frederick Mappin Building, Sheffield, S1 3JD, United Kingdom; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={In Section 2.7, the solution of heterogeneous, one-dimensional phase-field profiles with the intent to improve previous analytical correction approaches was brought into consideration in a personal communication by Keita Yoshioka, Helmholtz Centre for Environmental Research. © 2020},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={00137944},
      coden={EFMEA},
      language={English},
      abbrev_source_title={Eng. Fract. Mech.},
      document_type={Erratum},
      source={Scopus},
      }

  • Strong and Weak 3D Topological Insulators Probed by Surface Science Methods
    • M. Morgenstern, C. Pauly, J. Kellner, M. Liebmann, M. Pratzer, G. Bihlmayer, M. Eschbach, L. Plucinski, S. Otto, B. Rasche, M. Ruck, M. Richter, S. Just, F. Lüpke, B. Voigtländer
    • Physica Status Solidi (B) Basic Research 258, 2000060 (2021)
    • DOI   Abstract  

      The contributions of surface science methods to discover and improve 3D topological insulator materials are reviewed herein, illustrated with examples from the authors’ own work. In particular, it is demonstrated that spin-polarized angular-resolved photoelectron spectroscopy is instrumental to evidence the spin-helical surface Dirac cone, to tune its Dirac point energy toward the Fermi level, and to discover novel types of topological insulators such as dual ones or switchable ones in phase change materials. Moreover, procedures are introduced to spatially map potential fluctuations by scanning tunneling spectroscopy and to identify topological edge states in weak topological insulators. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

      @ARTICLE{Morgenstern2021,
      author={Morgenstern, M. and Pauly, C. and Kellner, J. and Liebmann, M. and Pratzer, M. and Bihlmayer, G. and Eschbach, M. and Plucinski, L. and Otto, S. and Rasche, B. and Ruck, M. and Richter, M. and Just, S. and Lüpke, F. and Voigtländer, B.},
      title={Strong and Weak 3D Topological Insulators Probed by Surface Science Methods},
      journal={Physica Status Solidi (B) Basic Research},
      year={2021},
      volume={258},
      number={1},
      doi={10.1002/pssb.202000060},
      art_number={2000060},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084510267&doi=10.1002%2fpssb.202000060&partnerID=40&md5=e4cfbdaaed2627f87f73b783792ea28d},
      affiliation={II. Institute of Physics B and JARA-FIT, RWTH Aachen University, Aachen, 52074, Germany; Peter Grünberg Institut (PGI-1), Institute for Advanced Simulation (IAS-1), Forschungszentrum Jülich GmbH and JARA, Jülich, 52425, Germany; Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH and JARA, Jülich, 52428, Germany; Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Erlangen, 91058, Germany; Faculty of Chemistry and Food Chemistry, TU Dresden, Dresden, 01062, Germany; Leibniz Institute for Solid State and Materials Research, Dresden Center for Computational Science, IFW Dresden, P.O. box 270116, Dresden, 01171, Germany; Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich GmbH and JARA, Jülich, 52428, Germany},
      abstract={The contributions of surface science methods to discover and improve 3D topological insulator materials are reviewed herein, illustrated with examples from the authors’ own work. In particular, it is demonstrated that spin-polarized angular-resolved photoelectron spectroscopy is instrumental to evidence the spin-helical surface Dirac cone, to tune its Dirac point energy toward the Fermi level, and to discover novel types of topological insulators such as dual ones or switchable ones in phase change materials. Moreover, procedures are introduced to spatially map potential fluctuations by scanning tunneling spectroscopy and to identify topological edge states in weak topological insulators. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim},
      author_keywords={angular-resolved photoelectron spectroscopy; scanning tunneling spectroscopy; spin-polarized topological insulators},
      keywords={Electric insulators; Photoelectron spectroscopy; Scanning tunneling microscopy; Topological insulators, Dirac cones; Dirac point; Helical surfaces; Potential fluctuations; Scanning tunneling spectroscopy; Spin-polarized; Surface science; Switchable, Phase change materials},
      correspondence_address1={Morgenstern, M.; II. Institute of Physics B and JARA-FIT, Germany; email: mmorgens@physik.rwth-aachen.de},
      publisher={Wiley-VCH Verlag},
      issn={03701972},
      language={English},
      abbrev_source_title={Phys. Status Solidi B Basic Res.},
      document_type={Article},
      source={Scopus},
      }

2020

  • Determination of the entire stent surface area by a new analytical method
    • M. Saqib, R. Bernhardt, M. Kästner, N. Beshchasna, G. Cuniberti, J. Opitz
    • Materials 13, 1-11 , 5633 (2020)
    • DOI   Abstract  

      Stenting is a widely used treatment procedure for coronary artery disease around the world. Stents have a complex geometry, which makes the characterization of their corrosion difficult due to the absence of a mathematical model to calculate the entire stent surface area (ESSA). Therefore, corrosion experiments with stents are mostly based on qualitative analysis. Additionally, the quantitative analysis of corrosion is conducted with simpler samples made of stent material instead of stents, in most cases. At present, several methods are available to calculate the stent outer surface area (SOSA), whereas no model exists for the calculation of the ESSA. This paper presents a novel mathematical model for the calculation of the ESSA using the SOSA as one of the main parameters. The ESSA of seven magnesium alloy stents (MeKo Laser Material Processing GmbH, Sarstedt, Germany) were calculated using the developed model. The calculated SOSA and ESSA for all stents are 33.34% (±0.26%) and 111.86 mm (±0.85 mm), respectively. The model is validated by micro-computed tomography (micro-CT), with a difference of 12.34% (±0.46%). The value of corrosion rates calculated using the ESSA computed with the developed model will be 12.34% (±0.46%) less than that of using ESSA obtained by micro-CT. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

      @ARTICLE{Saqib20201,
      author={Saqib, M. and Bernhardt, R. and Kästner, M. and Beshchasna, N. and Cuniberti, G. and Opitz, J.},
      title={Determination of the entire stent surface area by a new analytical method},
      journal={Materials},
      year={2020},
      volume={13},
      number={24},
      pages={1-11},
      doi={10.3390/ma13245633},
      art_number={5633},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85097530492&doi=10.3390%2fma13245633&partnerID=40&md5=0f7b4cc4e6c6eaf7c3e1cdc91130ddde},
      affiliation={Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Maria-Reiche-Strasse 2, Dresden, 01109, Germany; Faculty of Mechanical Science and Engineering, Institute of Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01062, Germany; Leibniz Institute of Polymer Research Dresden, Dresden, 01069, Germany; Faculty of Mechanical Science and Engineering, Institute of Solid Mechanics, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={Stenting is a widely used treatment procedure for coronary artery disease around the world. Stents have a complex geometry, which makes the characterization of their corrosion difficult due to the absence of a mathematical model to calculate the entire stent surface area (ESSA). Therefore, corrosion experiments with stents are mostly based on qualitative analysis. Additionally, the quantitative analysis of corrosion is conducted with simpler samples made of stent material instead of stents, in most cases. At present, several methods are available to calculate the stent outer surface area (SOSA), whereas no model exists for the calculation of the ESSA. This paper presents a novel mathematical model for the calculation of the ESSA using the SOSA as one of the main parameters. The ESSA of seven magnesium alloy stents (MeKo Laser Material Processing GmbH, Sarstedt, Germany) were calculated using the developed model. The calculated SOSA and ESSA for all stents are 33.34% (±0.26%) and 111.86 mm (±0.85 mm), respectively. The model is validated by micro-computed tomography (micro-CT), with a difference of 12.34% (±0.46%). The value of corrosion rates calculated using the ESSA computed with the developed model will be 12.34% (±0.46%) less than that of using ESSA obtained by micro-CT. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.},
      author_keywords={Corrosion; Degradation; Mass loss; Micro-CT; Quantitative corrosion test; Stents; Surface area},
      keywords={Computerized tomography; Corrosion rate; Diseases; Laser materials processing; Magnesium alloys, Analytical method; Complex geometries; Coronary artery disease; Developed model; Laser material processing; Main parameters; Micro computed tomography (micro-CT); Qualitative analysis, Stents},
      correspondence_address1={Saqib, M.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Maria-Reiche-Strasse 2, Germany; email: muhammad.saqib@ikts.fraunhofer.de; Saqib, M.; Faculty of Mechanical Science and Engineering, Germany; email: muhammad.saqib@ikts.fraunhofer.de; Beshchasna, N.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Maria-Reiche-Strasse 2, Germany; email: natalia.beshchasna@ikts.fraunhofer.de; Cuniberti, G.; Faculty of Mechanical Science and Engineering, Germany; email: g.cuniberti@tu-dresden.de; Cuniberti, G.; Dresden Center for Computational Materials Science, Germany; email: g.cuniberti@tu-dresden.de; Cuniberti, G.; Center for Advancing Electronics Dresden, Germany; email: g.cuniberti@tu-dresden.de; Opitz, J.; Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Maria-Reiche-Strasse 2, Germany; email: joerg.opitz@ikts.fraunhofer.de; Opitz, J.; Faculty of Mechanical Science and Engineering, Germany; email: joerg.opitz@ikts.fraunhofer.de},
      publisher={MDPI AG},
      issn={19961944},
      language={English},
      abbrev_source_title={Mater.},
      document_type={Article},
      source={Scopus},
      }

  • A simulation method for particle migration in microfluidic spirals with application to small and medium particle concentrations
    • T. Hafemann, S. Tschisgale, J. Fröhlich
    • Physics of Fluids 32, 123303 (2020)
    • DOI   Abstract  

      This paper treats the separation of particles in microchannels relevant to biological and industrial process engineering. To elucidate the mechanisms creating uneven distribution of particles over the cross section, simulations are conducted with the particles being geometrically resolved and coupled to the fluid by an immersed-boundary method. In a first step, the method is validated for particle focusing in straight channels. Beyond validation, new information not previously available is reported for these cases. Next, an efficient approach is presented to simulate the motion of particles in spiral ducts of small curvature by means of a well-controlled set of approximate equations. It is applied here to situations with spherical particles and validated with reference data for inertial migration in curved channels achieving good agreement. The simulation data provide new rich information on the details of the separation process concerning migration time, particle positioning in the cross section, streamwise particle spacing, and velocity field of the continuous phase. For concentrations smaller than 1%, three different focusing modes are observed: single position, two symmetric positions, and periodic trajectories oscillating between two focusing points. Another set of results is obtained with particle concentrations up to 10% in a curved channel. Here, the spatial distribution of particles is determined in a statistical sense and related to the mean flow of the continuous phase. While focusing is reduced with increasing particle concentration, the distribution of particles is found to be still far from uniform up to the investigated concentration level. © 2020 Author(s).

      @ARTICLE{Hafemann2020,
      author={Hafemann, T. and Tschisgale, S. and Fröhlich, J.},
      title={A simulation method for particle migration in microfluidic spirals with application to small and medium particle concentrations},
      journal={Physics of Fluids},
      year={2020},
      volume={32},
      number={12},
      doi={10.1063/5.0024472},
      art_number={123303},
      note={cited By 7},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85097330589&doi=10.1063%2f5.0024472&partnerID=40&md5=61dbedee403c5d03469dfe549b487633},
      affiliation={Chair of Fluid Mechanics, Tu Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Tu Dresden, Dresden, 01062, Germany; Institute of Air Handling and Refrigeration, Dresden, 01309, Germany},
      abstract={This paper treats the separation of particles in microchannels relevant to biological and industrial process engineering. To elucidate the mechanisms creating uneven distribution of particles over the cross section, simulations are conducted with the particles being geometrically resolved and coupled to the fluid by an immersed-boundary method. In a first step, the method is validated for particle focusing in straight channels. Beyond validation, new information not previously available is reported for these cases. Next, an efficient approach is presented to simulate the motion of particles in spiral ducts of small curvature by means of a well-controlled set of approximate equations. It is applied here to situations with spherical particles and validated with reference data for inertial migration in curved channels achieving good agreement. The simulation data provide new rich information on the details of the separation process concerning migration time, particle positioning in the cross section, streamwise particle spacing, and velocity field of the continuous phase. For concentrations smaller than 1%, three different focusing modes are observed: single position, two symmetric positions, and periodic trajectories oscillating between two focusing points. Another set of results is obtained with particle concentrations up to 10% in a curved channel. Here, the spatial distribution of particles is determined in a statistical sense and related to the mean flow of the continuous phase. While focusing is reduced with increasing particle concentration, the distribution of particles is found to be still far from uniform up to the investigated concentration level. © 2020 Author(s).},
      keywords={Microfluidics; Turbulent flow; Velocity, Approximate equation; Concentration levels; Distribution of particles; Immersed boundary methods; Industrial process engineering; Motion of particles; Particle concentrations; Periodic trajectories, Focusing},
      correspondence_address1={Hafemann, T.; Chair of Fluid Mechanics, Germany; email: thomas.hafemann@tu-dresden.de},
      publisher={American Institute of Physics Inc.},
      issn={10706631},
      coden={PHFLE},
      language={English},
      abbrev_source_title={Phys. Fluids},
      document_type={Article},
      source={Scopus},
      }

  • The Weak 3D Topological Insulator Bi12Rh3Sn3I9
    • M. Lê Anh, M. Kaiser, M. P. Ghimire, M. Richter, K. Koepernik, M. Gruschwitz, C. Tegenkamp, T. Doert, M. Ruck
    • Chemistry – A European Journal 26, 15549-15557 (2020)
    • DOI   Abstract  

      Topological insulators (TIs) gained high interest due to their protected electronic surface states that allow dissipation-free electron and information transport. In consequence, TIs are recommended as materials for spintronics and quantum computing. Yet, the number of well-characterized TIs is rather limited. To contribute to this field of research, we focused on new bismuth-based subiodides and recently succeeded in synthesizing a new compound Bi12Rh3Sn3I9, which is structurally closely related to Bi14Rh3I9 – a stable, layered material. In fact, Bi14Rh3I9 is the first experimentally supported weak 3D TI. Both structures are composed of well-defined intermetallic layers of ∞2[(Bi4Rh)3I]2+ with topologically protected electronic edge-states. The fundamental difference between Bi14Rh3I9 and Bi12Rh3Sn3I9 lies in the composition and the arrangement of the anionic spacer. While the intermetallic 2D TI layers in Bi14Rh3I9 are isolated by ∞1[Bi2I8]2− chains, the isoelectronic substitution of bismuth(III) with tin(II) leads to ∞2[Sn3I8]2− layers as anionic spacers. First transport experiments support the 2D character of this material class and revealed metallic conductivity. © 2020 The Authors. Published by Wiley-VCH GmbH

      @ARTICLE{LêAnh202015549,
      author={Lê Anh, M. and Kaiser, M. and Ghimire, M.P. and Richter, M. and Koepernik, K. and Gruschwitz, M. and Tegenkamp, C. and Doert, T. and Ruck, M.},
      title={The Weak 3D Topological Insulator Bi12Rh3Sn3I9},
      journal={Chemistry - A European Journal},
      year={2020},
      volume={26},
      number={67},
      pages={15549-15557},
      doi={10.1002/chem.202001953},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092060259&doi=10.1002%2fchem.202001953&partnerID=40&md5=6f8b24e793798732103914f88a2b51d8},
      affiliation={Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden, 01062, Germany; Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, Nepal; Leibniz IFW Dresden, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Institute of Physics, Technische Universität Chemnitz, Chemnitz, 09126, Germany; Max Planck Institute for Chemical Physics of Solids, Dresden, 01187, Germany},
      abstract={Topological insulators (TIs) gained high interest due to their protected electronic surface states that allow dissipation-free electron and information transport. In consequence, TIs are recommended as materials for spintronics and quantum computing. Yet, the number of well-characterized TIs is rather limited. To contribute to this field of research, we focused on new bismuth-based subiodides and recently succeeded in synthesizing a new compound Bi12Rh3Sn3I9, which is structurally closely related to Bi14Rh3I9 – a stable, layered material. In fact, Bi14Rh3I9 is the first experimentally supported weak 3D TI. Both structures are composed of well-defined intermetallic layers of ∞2[(Bi4Rh)3I]2+ with topologically protected electronic edge-states. The fundamental difference between Bi14Rh3I9 and Bi12Rh3Sn3I9 lies in the composition and the arrangement of the anionic spacer. While the intermetallic 2D TI layers in Bi14Rh3I9 are isolated by ∞1[Bi2I8]2− chains, the isoelectronic substitution of bismuth(III) with tin(II) leads to ∞2[Sn3I8]2− layers as anionic spacers. First transport experiments support the 2D character of this material class and revealed metallic conductivity. © 2020 The Authors. Published by Wiley-VCH GmbH},
      author_keywords={crystal growth; crystal structure; topological band gap; topological insulators; weak topological insulators},
      keywords={Electric insulators; Electrons; Intermetallics; Quantum computers; Rhodium compounds; Shims; Tin compounds; Topological insulators, Electronic surface state; Information transport; Intermetallic layer; Isoelectronic substitution; Layered material; Metallic conductivity; Quantum Computing; Transport experiments, Bismuth compounds, article; conductance; controlled study; crystallization; field study},
      correspondence_address1={Ruck, M.; Faculty of Chemistry and Food Chemistry, Germany; email: michael.ruck@tu-dresden.de; Ruck, M.; Max Planck Institute for Chemical Physics of SolidsGermany; email: michael.ruck@tu-dresden.de},
      publisher={Wiley-VCH Verlag},
      issn={09476539},
      coden={CEUJE},
      pubmed_id={32490557},
      language={English},
      abbrev_source_title={Chem. Eur. J.},
      document_type={Article},
      source={Scopus},
      }

  • Erratum: Field-induced interactions in magneto-active elastomers — A comparison of experiments and simulations (Smart Materials and Structures (2020) 29 (085026) DOI: 10.13039/501100001659)
    • P. Metsch, H. Schmidt, D. Sindersberger, K. A. Kalina, J. Brummund, G. K. Auernhammer, G. J. Monkman, M. Kästner
    • Smart Materials and Structures 29, 119501 (2020)
    • DOI   Abstract  

      (Figure Presented). The authors would like to correct an erroneous picture within the published paper that was accidentally regenerated using wrong data after the revision process. On page 6 in the published paper, figure 6(b) shows wrong results for the two-dimensional simulation (dashed, gray line). The results shown in the picture are in contradiction with the given explanations on the same page and, thus, figure 6(b) should be replaced by the original, correct version that is shown here. © 2020 IOP Publishing Ltd.

      @ARTICLE{Metsch2020,
      author={Metsch, P. and Schmidt, H. and Sindersberger, D. and Kalina, K.A. and Brummund, J. and Auernhammer, G.K. and Monkman, G.J. and Kästner, M.},
      title={Erratum: Field-induced interactions in magneto-active elastomers — A comparison of experiments and simulations (Smart Materials and Structures (2020) 29 (085026) DOI: 10.13039/501100001659)},
      journal={Smart Materials and Structures},
      year={2020},
      volume={29},
      number={11},
      doi={10.1088/1361-665X/abb98b},
      art_number={119501},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85095884853&doi=10.1088%2f1361-665X%2fabb98b&partnerID=40&md5=15bd770581b6a66b79b3da28cb9ead18},
      affiliation={Institute of Solid Mechanics, Technische Universität Dresden, Dresden, 01062, Germany; Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany; Mechatronics Research Unit, OTH Regensburg, Regensburg, Germany; Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, Germany},
      abstract={(Figure Presented). The authors would like to correct an erroneous picture within the published paper that was accidentally regenerated using wrong data after the revision process. On page 6 in the published paper, figure 6(b) shows wrong results for the two-dimensional simulation (dashed, gray line). The results shown in the picture are in contradiction with the given explanations on the same page and, thus, figure 6(b) should be replaced by the original, correct version that is shown here. © 2020 IOP Publishing Ltd.},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={IOP Publishing Ltd},
      issn={09641726},
      coden={SMSTE},
      language={English},
      abbrev_source_title={Smart Mater Struct},
      document_type={Erratum},
      source={Scopus},
      }

  • Flow-Induced Formation of Thin PEO Fibers in Water and Their Stability after the Strain Release
    • S. Donets, O. Guskova, J. -U. Sommer
    • Journal of Physical Chemistry B 124, 9224-9229 (2020)
    • DOI   Abstract  

      Recently, we have shown that a tensile stress applied to chains of poly(ethylene oxide) (PEO) in water reduces the solubility and leads to phase separation of PEO chains from water with the formation of a two-phase region. In this work, we further elucidate the generic mechanism behind strain-induced phase transitions in aqueous PEO solutions with concentrations of 50-60 wt % by performing all-atom molecular dynamics simulations. In particular, we study the stability of oriented PEO fibers after removing stretching forces. We found that the size of the PEO bundle increased with time, which is associated with the dissolution of PEO chains on the fiber surface due to the reformation of hydrogen bonds between the outer PEO molecules and water. For precise characterization of the fibers, the scattering patterns (small- and wide-angle X-ray spectra) for configurations taken at different relaxation times are calculated. The tendency of the oligomer chains to be peeled off from the surface of the bundle eventually might lead to a complete dissolution of the PEO fiber. We conclude that either entanglement constraints or a quick drying process are necessary to conserve the fiber structure in a quiescent state. The scattering results show that external strain induced a liquid-liquid phase separation first. On long time scales, this can be a precursor for crystallization of the fiber. © 2020 American Chemical Society.

      @ARTICLE{Donets20209224,
      author={Donets, S. and Guskova, O. and Sommer, J.-U.},
      title={Flow-Induced Formation of Thin PEO Fibers in Water and Their Stability after the Strain Release},
      journal={Journal of Physical Chemistry B},
      year={2020},
      volume={124},
      number={41},
      pages={9224-9229},
      doi={10.1021/acs.jpcb.0c05627},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85093539138&doi=10.1021%2facs.jpcb.0c05627&partnerID=40&md5=e0e866f846ac96917c6b0ca79a8e97d9},
      affiliation={Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Institute of Theoretical Physics, Technische Universität Dresden, Zellescher Weg 17, Dresden, 01069, Germany},
      abstract={Recently, we have shown that a tensile stress applied to chains of poly(ethylene oxide) (PEO) in water reduces the solubility and leads to phase separation of PEO chains from water with the formation of a two-phase region. In this work, we further elucidate the generic mechanism behind strain-induced phase transitions in aqueous PEO solutions with concentrations of 50-60 wt % by performing all-atom molecular dynamics simulations. In particular, we study the stability of oriented PEO fibers after removing stretching forces. We found that the size of the PEO bundle increased with time, which is associated with the dissolution of PEO chains on the fiber surface due to the reformation of hydrogen bonds between the outer PEO molecules and water. For precise characterization of the fibers, the scattering patterns (small- and wide-angle X-ray spectra) for configurations taken at different relaxation times are calculated. The tendency of the oligomer chains to be peeled off from the surface of the bundle eventually might lead to a complete dissolution of the PEO fiber. We conclude that either entanglement constraints or a quick drying process are necessary to conserve the fiber structure in a quiescent state. The scattering results show that external strain induced a liquid-liquid phase separation first. On long time scales, this can be a precursor for crystallization of the fiber. © 2020 American Chemical Society.},
      keywords={Dissolution; Ethylene; Fibers; Hydrogen bonds; Molecular dynamics; Polyethylene oxides; Quantum entanglement, Complete dissolution; External strains; Fiber structures; Generic mechanism; Liquid-liquid phase separation; Molecular dynamics simulations; Poly (ethylene oxide) (PEO); Scattering pattern, Phase separation},
      correspondence_address1={Donets, S.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: donets@ipfdd.de; Sommer, J.-U.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: sommer@ipfdd.de},
      publisher={American Chemical Society},
      issn={15206106},
      coden={JPCBF},
      pubmed_id={32935989},
      language={English},
      abbrev_source_title={J Phys Chem B},
      document_type={Article},
      source={Scopus},
      }

  • Role of Exchange Interactions in the Magnetic Response and Intermolecular Recognition of Chiral Molecules
    • A. Dianat, R. Gutierrez, H. Alpern, V. Mujica, A. Ziv, S. Yochelis, O. Millo, Y. Paltiel, G. Cuniberti
    • Nano Letters 20, 7077-7086 (2020)
    • DOI   Abstract  

      The physical origin of the so-called chirality-induced spin selectivity (CISS) effect has puzzled experimental and theoretical researchers over the past few years. Early experiments were interpreted in terms of unconventional spin-orbit interactions mediated by the helical geometry. However, more recent experimental studies have clearly revealed that electronic exchange interactions also play a key role in the magnetic response of chiral molecules in singlet states. In this investigation, we use spin-polarized closed-shell density functional theory calculations to address the influence of exchange contributions to the interaction between helical molecules as well as of helical molecules with magnetized substrates. We show that exchange effects result in differences in the interaction properties with magnetized surfaces, shedding light into the possible origin of two recent important experimental results: enantiomer separation and magnetic exchange force microscopy with AFM tips functionalized with helical peptides. Copyright © 2020 American Chemical Society.

      @ARTICLE{Dianat20207077,
      author={Dianat, A. and Gutierrez, R. and Alpern, H. and Mujica, V. and Ziv, A. and Yochelis, S. and Millo, O. and Paltiel, Y. and Cuniberti, G.},
      title={Role of Exchange Interactions in the Magnetic Response and Intermolecular Recognition of Chiral Molecules},
      journal={Nano Letters},
      year={2020},
      volume={20},
      number={10},
      pages={7077-7086},
      doi={10.1021/acs.nanolett.0c02216},
      note={cited By 18},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092944916&doi=10.1021%2facs.nanolett.0c02216&partnerID=40&md5=5276dd9b4122504d51c64b1000e7bff5},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, Tu Dresden, Dresden, 01062, Germany; Applied Physics Department, Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, 9190401, Israel; Racah Institute of Physics, Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, 9190401, Israel; School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, United States; Ikerbasque Foundation and Donostia International Physics Center (DIPC), Manuel de Lardizabal Pasealekua 4, Donostia, Euskadi 20018, Spain; Applied Physics Department, Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, 9190401, Israel; Dresden Center for Computational Materials Science (DCMS), Tu Dresden, Dresden, 01062, Germany},
      abstract={The physical origin of the so-called chirality-induced spin selectivity (CISS) effect has puzzled experimental and theoretical researchers over the past few years. Early experiments were interpreted in terms of unconventional spin-orbit interactions mediated by the helical geometry. However, more recent experimental studies have clearly revealed that electronic exchange interactions also play a key role in the magnetic response of chiral molecules in singlet states. In this investigation, we use spin-polarized closed-shell density functional theory calculations to address the influence of exchange contributions to the interaction between helical molecules as well as of helical molecules with magnetized substrates. We show that exchange effects result in differences in the interaction properties with magnetized surfaces, shedding light into the possible origin of two recent important experimental results: enantiomer separation and magnetic exchange force microscopy with AFM tips functionalized with helical peptides. Copyright © 2020 American Chemical Society.},
      author_keywords={broken symmetry; CISS effect; Density-Functional Theory; Exchange Effects; Helical Molecules},
      keywords={Density functional theory; Exchange interactions; Magnetism; Molecules; Spin orbit coupling, Enantiomer separation; Exchange effects; Helical molecules; Interaction properties; Intermolecular recognition; Magnetic exchange; Magnetic response; Spin orbit interactions, Stereochemistry},
      correspondence_address1={Dianat, A.; Institute for Materials Science, Germany; email: arezoo.dianat@tu-dresden.de; Gutierrez, R.; Institute for Materials Science, Germany; email: rafael.gutierrez@tu-dresden.de; Cuniberti, G.; Institute for Materials Science, Germany; email: gianaurelio.cuniberti@tu-dresden.de},
      publisher={American Chemical Society},
      issn={15306984},
      coden={NALEF},
      pubmed_id={32786950},
      language={English},
      abbrev_source_title={Nano Lett.},
      document_type={Article},
      source={Scopus},
      }

  • Interactions of long-chain polyamines with silica studied by molecular dynamics simulations and solid-state NMR spectroscopy
    • E. Brunner, G. Cuniberti, M. Montagna, S. I. Brückner, A. Dianat, R. Gutierrez, F. Daus, A. Geyer
    • Langmuir 36, 11600-11609 (2020)
    • DOI   Abstract  

      The investigation of molecular interactions between silica phases and organic components is crucial for elucidating the main steps involved in the biosilica mineralization process. In this respect, the structural characterization of the organic/ inorganic interface is particularly useful for a deeper understanding of the dominant mechanisms of biomineralization. In this work, we have investigated the interaction of selectively 13C- and 15N-labeled atoms of organic long-chain polyamines (LCPAs) with 29Si-labeled atoms of a silica layer at the molecular level. In particular, silica/ LCPA nanocomposites were analyzed by solid-state NMR spectroscopy in combination with all-atom molecular dynamics simulations. Solid-state NMR experiments allow the determination of 29Si-15N and 29Si-13C internuclear distances, providing the parameters for direct verification of atomistic simulations. Our results elucidate the relevant molecular conformations as well as the nature of the interaction between the LCPA and a silica substrate. Specifically, distances and second moments suggest a picture compatible with (i) LCPA completely embedded in the silica phase and (ii) the charged amino groups located in close vicinity of silanol groups. © 2020 American Chemical Society.

      @ARTICLE{Brunner202011600,
      author={Brunner, E. and Cuniberti, G. and Montagna, M. and Brückner, S.I. and Dianat, A. and Gutierrez, R. and Daus, F. and Geyer, A.},
      title={Interactions of long-chain polyamines with silica studied by molecular dynamics simulations and solid-state NMR spectroscopy},
      journal={Langmuir},
      year={2020},
      volume={36},
      number={39},
      pages={11600-11609},
      doi={10.1021/acs.langmuir.0c02157},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092682553&doi=10.1021%2facs.langmuir.0c02157&partnerID=40&md5=64549b4a74d42301e33ea220e8174e91},
      affiliation={Faculty of Chemistry and Food Chemistry, Tu Dresden, Dresden, 01062, Germany; Institute for Materials Science, Max Bergmann Center of Biomaterials, Tu Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Tu Dresden, Dresden, 01062, Germany; Department of Chemistry, Philipps-University Marburg, Marburg, 35032, Germany},
      abstract={The investigation of molecular interactions between silica phases and organic components is crucial for elucidating the main steps involved in the biosilica mineralization process. In this respect, the structural characterization of the organic/ inorganic interface is particularly useful for a deeper understanding of the dominant mechanisms of biomineralization. In this work, we have investigated the interaction of selectively 13C- and 15N-labeled atoms of organic long-chain polyamines (LCPAs) with 29Si-labeled atoms of a silica layer at the molecular level. In particular, silica/ LCPA nanocomposites were analyzed by solid-state NMR spectroscopy in combination with all-atom molecular dynamics simulations. Solid-state NMR experiments allow the determination of 29Si-15N and 29Si-13C internuclear distances, providing the parameters for direct verification of atomistic simulations. Our results elucidate the relevant molecular conformations as well as the nature of the interaction between the LCPA and a silica substrate. Specifically, distances and second moments suggest a picture compatible with (i) LCPA completely embedded in the silica phase and (ii) the charged amino groups located in close vicinity of silanol groups. © 2020 American Chemical Society.},
      keywords={Amines; Atoms; Biomineralization; Light polarization; Nuclear magnetic resonance spectroscopy; Silica; Silicon, Atomistic simulations; Internuclear distances; Mineralization process; Molecular conformation; Molecular dynamics simulations; Organic-inorganic interface; Solid-state NMR spectroscopy; Structural characterization, Molecular dynamics},
      correspondence_address1={Brunner, E.; Faculty of Chemistry and Food Chemistry, Germany; email: eike.brunner@tu-dresden.de; Cuniberti, G.; Institute for Materials Science, Germany; email: gianaurelio.cuniberti@tudresden.de},
      publisher={American Chemical Society},
      issn={07437463},
      coden={LANGD},
      pubmed_id={32924496},
      language={English},
      abbrev_source_title={Langmuir},
      document_type={Article},
      source={Scopus},
      }

  • Sensitivity to strains and defects for manipulating the conductivity of graphene
    • I. Sahalianov, T. M. Radchenko, V. A. Tatarenko, G. Cuniberti
    • EPL 132, 48002 (2020)
    • DOI   Abstract  

      Implementing the quantum-mechanical Kubo-Greenwood formalism for the numerical calculation of dc conductivity, we demonstrate that the electron transport properties of a graphene layer can be tailored through the combined effect of defects (point and line scatterers) and strains (uniaxial tension and shear), which are commonly present in a graphene sample due to the features of its growth procedure and when the sample is used in devices. Motivated by two experimental works (He X. et al. Appl. Phys. Lett., 104 (2014) 243108; 105 (2014) 083108), where authors did not observe the transport gap even at large (22.5% of tensile and 16.7% of shear) deformations, we explain possible reasons, emphasizing on graphene’s strain and defect sensing. The strain- and defect-induced electron-hole asymmetry and anisotropy of conductivity, and its nonmonotony as a function of deformation suggest perspectives for the strain-defect engineering of electrotransport properties of graphene and related 2D materials. Copyright © 2020 EPLA.

      @ARTICLE{Sahalianov2020,
      author={Sahalianov, I.Yu. and Radchenko, T.M. and Tatarenko, V.A. and Cuniberti, G.},
      title={Sensitivity to strains and defects for manipulating the conductivity of graphene},
      journal={EPL},
      year={2020},
      volume={132},
      number={4},
      doi={10.1209/0295-5075/132/48002},
      art_number={48002},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85099830534&doi=10.1209%2f0295-5075%2f132%2f48002&partnerID=40&md5=c8b76d43bc428ffcf083bf9ad5c53ca7},
      affiliation={Linköping University, Norrköping, 60174, Sweden; G. V. Kurdyumov Institute for Metal Physics of the NAS of Ukraine, Kyiv, 03142, Ukraine; Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany},
      abstract={Implementing the quantum-mechanical Kubo-Greenwood formalism for the numerical calculation of dc conductivity, we demonstrate that the electron transport properties of a graphene layer can be tailored through the combined effect of defects (point and line scatterers) and strains (uniaxial tension and shear), which are commonly present in a graphene sample due to the features of its growth procedure and when the sample is used in devices. Motivated by two experimental works (He X. et al. Appl. Phys. Lett., 104 (2014) 243108; 105 (2014) 083108), where authors did not observe the transport gap even at large (22.5% of tensile and 16.7% of shear) deformations, we explain possible reasons, emphasizing on graphene's strain and defect sensing. The strain- and defect-induced electron-hole asymmetry and anisotropy of conductivity, and its nonmonotony as a function of deformation suggest perspectives for the strain-defect engineering of electrotransport properties of graphene and related 2D materials. Copyright © 2020 EPLA.},
      publisher={IOP Publishing Ltd},
      issn={02955075},
      language={English},
      abbrev_source_title={EPL},
      document_type={Article},
      source={Scopus},
      }

  • Hyperuniform monocrystalline structures by spinodal solid-state dewetting
    • M. Salvalaglio, M. Bouabdellaoui, M. Bollani, A. Benali, L. Favre, J. -B. Claude, J. Wenger, P. De Anna, F. Intonti, A. Voigt, M. Abbarchi
    • Physical Review Letters 125, 126101 (2020)
    • DOI   Abstract  

      Materials featuring anomalous suppression of density fluctuations over large length scales are emerging systems known as disordered hyperuniform. The underlying hidden order renders them appealing for several applications, such as light management and topologically protected electronic states. These applications require scalable fabrication, which is hard to achieve with available top-down approaches. Theoretically, it is known that spinodal decomposition can lead to disordered hyperuniform architectures. Spontaneous formation of stable patterns could thus be a viable path for the bottom-up fabrication of these materials. Here, we show that monocrystalline semiconductor-based structures, in particular Si1-xGex layers deposited on silicon-on-insulator substrates, can undergo spinodal solid-state dewetting featuring correlated disorder with an effective hyperuniform character. Nano- to micrometric sized structures targeting specific morphologies and hyperuniform character can be obtained, proving the generality of the approach and paving the way for technological applications of disordered hyperuniform metamaterials. Phase-field simulations explain the underlying nonlinear dynamics and the physical origin of the emerging patterns. © 2020 American Physical Society.

      @ARTICLE{Salvalaglio2020,
      author={Salvalaglio, M. and Bouabdellaoui, M. and Bollani, M. and Benali, A. and Favre, L. and Claude, J.-B. and Wenger, J. and De Anna, P. and Intonti, F. and Voigt, A. and Abbarchi, M.},
      title={Hyperuniform monocrystalline structures by spinodal solid-state dewetting},
      journal={Physical Review Letters},
      year={2020},
      volume={125},
      number={12},
      doi={10.1103/PhysRevLett.125.126101},
      art_number={126101},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85092427244&doi=10.1103%2fPhysRevLett.125.126101&partnerID=40&md5=3431987fa642bf5f2d02d7530d42c695},
      affiliation={Institute of Scientific Computing, Tu Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Tu Dresden, Dresden, 01062, Germany; Aix Marseille Univ, Université de Toulon, Cnrs, IM2NP, Marseille, 13397, France; Istituto di Fotonica e Nanotecnologie-Consiglio Nazionale Delle Ricerche, Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Via Anzani 42, Como, 22100, Italy; Aix Marseille Université, Cnrs, Centrale Marseille, Institut Fresnel, Marseille, 13013, France; Institut des Sciences de la Terre, University of Lausanne, Lausanne, 1015, Switzerland; Lens, University of Florence, Sesto Fiorentino, 50019, Italy},
      abstract={Materials featuring anomalous suppression of density fluctuations over large length scales are emerging systems known as disordered hyperuniform. The underlying hidden order renders them appealing for several applications, such as light management and topologically protected electronic states. These applications require scalable fabrication, which is hard to achieve with available top-down approaches. Theoretically, it is known that spinodal decomposition can lead to disordered hyperuniform architectures. Spontaneous formation of stable patterns could thus be a viable path for the bottom-up fabrication of these materials. Here, we show that monocrystalline semiconductor-based structures, in particular Si1-xGex layers deposited on silicon-on-insulator substrates, can undergo spinodal solid-state dewetting featuring correlated disorder with an effective hyperuniform character. Nano- to micrometric sized structures targeting specific morphologies and hyperuniform character can be obtained, proving the generality of the approach and paving the way for technological applications of disordered hyperuniform metamaterials. Phase-field simulations explain the underlying nonlinear dynamics and the physical origin of the emerging patterns. © 2020 American Physical Society.},
      keywords={Semiconductor alloys; Si-Ge alloys; Silicon on insulator technology; Substrates, Bottom-up fabrication; Monocrystalline semiconductors; Monocrystalline structures; Phase-field simulation; Silicon-on-insulator substrates; Spontaneous formation; Technological applications; Top down approaches, Spinodal decomposition},
      publisher={American Physical Society},
      issn={00319007},
      coden={PRLTA},
      pubmed_id={33016725},
      language={English},
      abbrev_source_title={Phys Rev Lett},
      document_type={Article},
      source={Scopus},
      }

  • Universal Limit for Air-Stable Molecular n-Doping in Organic Semiconductors
    • M. Schwarze, M. L. Tietze, F. Ortmann, H. Kleemann, K. Leo
    • ACS Applied Materials and Interfaces 12, 40566-40571 (2020)
    • DOI   Abstract  

      The air sensitivity of n-doped layers is crucial for the long-term stability of organic electronic devices. Although several air-stable and highly efficient n-dopants have been developed, the reason for the varying air sensitivity between different n-doped layers, in which the n-dopant molecules are dispersed, is not fully understood. In contrast to previous studies that compared the air stability of doped films with the energy levels of neat host or dopant layers, we trace back the varying degree of air sensitivity to the energy levels of integer charge transfer states (ICTCs) formed by host anions and dopant cations. Our data indicate a universal limit for the ionization energy of ICTCs above which the n-doped semiconductors are air-stable. © 2020 American Chemical Society.

      @ARTICLE{Schwarze202040566,
      author={Schwarze, M. and Tietze, M.L. and Ortmann, F. and Kleemann, H. and Leo, K.},
      title={Universal Limit for Air-Stable Molecular n-Doping in Organic Semiconductors},
      journal={ACS Applied Materials and Interfaces},
      year={2020},
      volume={12},
      number={36},
      pages={40566-40571},
      doi={10.1021/acsami.0c04380},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090870344&doi=10.1021%2facsami.0c04380&partnerID=40&md5=719ea2a9bea7159ee921359afd94a68c},
      affiliation={Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01069, Germany},
      abstract={The air sensitivity of n-doped layers is crucial for the long-term stability of organic electronic devices. Although several air-stable and highly efficient n-dopants have been developed, the reason for the varying air sensitivity between different n-doped layers, in which the n-dopant molecules are dispersed, is not fully understood. In contrast to previous studies that compared the air stability of doped films with the energy levels of neat host or dopant layers, we trace back the varying degree of air sensitivity to the energy levels of integer charge transfer states (ICTCs) formed by host anions and dopant cations. Our data indicate a universal limit for the ionization energy of ICTCs above which the n-doped semiconductors are air-stable. © 2020 American Chemical Society.},
      author_keywords={air-stable n-doping; electrical conductivity; electron trap; Fermi level; integer charge transfer complex; molecular doping; photoelectron spectroscopy; universal limit},
      keywords={Charge transfer, Air stability; Charge transfer state; Dopant cation; Dopant molecules; Doped films; Long term stability; N-doped semiconductor; Organic electronic devices, Semiconductor doping},
      correspondence_address1={Leo, K.; Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Germany; email: karl.leo@iapp.de},
      publisher={American Chemical Society},
      issn={19448244},
      pubmed_id={32805922},
      language={English},
      abbrev_source_title={ACS Appl. Mater. Interfaces},
      document_type={Article},
      source={Scopus},
      }

  • Nanocytometer for smart analysis of peripheral blood and acute myeloid leukemia: A pilot study
    • J. Schütt, D. I. Sandoval Bojorquez, E. Avitabile, E. S. Oliveros Mata, G. Milyukov, J. Colditz, L. G. Delogu, M. Rauner, A. Feldmann, S. Koristka, J. M. Middeke, K. Sockel, J. Fassbender, M. Bachmann, M. Bornhäuser, G. Cuniberti, L. Baraban
    • Nano Letters 20, 6572-6581 (2020)
    • DOI   Abstract  

      We realize an ultracompact nanocytometer for real-time impedimetric detection and classification of subpopulations of living cells. Nanoscopic nanowires in a microfluidic channel act as nanocapacitors and measure in real time the change of the amplitude and phase of the output voltage and, thus, the electrical properties of living cells. We perform the cell classification in the human peripheral blood (PBMC) and demonstrate for the first time the possibility to discriminate monocytes and subpopulations of lymphocytes in a label-free format. Further, we demonstrate that the PBMC of acute myeloid leukemia and healthy samples grant the label free identification of the disease. Using the algorithm based on machine learning, we generated specific data patterns to discriminate healthy donors and leukemia patients. Such a solution has the potential to improve the traditional diagnostics approaches with respect to the overall cost and time effort, in a label-free format, and restrictions of the complex data analysis. © 2020 American Chemical Society.

      @ARTICLE{Schütt20206572,
      author={Schütt, J. and Sandoval Bojorquez, D.I. and Avitabile, E. and Oliveros Mata, E.S. and Milyukov, G. and Colditz, J. and Delogu, L.G. and Rauner, M. and Feldmann, A. and Koristka, S. and Middeke, J.M. and Sockel, K. and Fassbender, J. and Bachmann, M. and Bornhäuser, M. and Cuniberti, G. and Baraban, L.},
      title={Nanocytometer for smart analysis of peripheral blood and acute myeloid leukemia: A pilot study},
      journal={Nano Letters},
      year={2020},
      volume={20},
      number={9},
      pages={6572-6581},
      doi={10.1021/acs.nanolett.0c02300},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85090613693&doi=10.1021%2facs.nanolett.0c02300&partnerID=40&md5=82f2185f39a0003f96d440c6b7ae8877},
      affiliation={Max Bergmann Center of Biomaterials, Institute for Materials Science, Dresden University of Technology, Budapesterstrasse 27, Dresden, 01069, Germany; Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf E.V., Bautzner Landstrasse 400, Dresden, 01328, Germany; Department of Chemistry and Pharmacy, University of Sassari, via muroni 23, Sassari, 07100, Italy; Samsung R and D Institute Russia (SRR), Moscow, 127018, Russian Federation; Department of Biomedical Sciences, University of Padua, via Ugo bassi 58, Padua, 35122, Italy; Medizinische Klinik und Poliklinik i, Universitätsklinikum Carl Gustav Carus Dresden, Dresden, 01307, Germany; Medizinische Klinik und Poliklinik III, Universitätsklinikum Carl Gustav Carus Dresden, Dresden, 01307, Germany; Center for Advancing Electronics Dresden (Cfaed), Technische Universität Dresden, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf E.V., Bautzner Landstrasse 400, Dresden, 01328, Germany; Else Kröner-Fresenius Center for Digital Health (EKFZ), Technische Universität Dresden (TU Dresden), Dresden, Germany},
      abstract={We realize an ultracompact nanocytometer for real-time impedimetric detection and classification of subpopulations of living cells. Nanoscopic nanowires in a microfluidic channel act as nanocapacitors and measure in real time the change of the amplitude and phase of the output voltage and, thus, the electrical properties of living cells. We perform the cell classification in the human peripheral blood (PBMC) and demonstrate for the first time the possibility to discriminate monocytes and subpopulations of lymphocytes in a label-free format. Further, we demonstrate that the PBMC of acute myeloid leukemia and healthy samples grant the label free identification of the disease. Using the algorithm based on machine learning, we generated specific data patterns to discriminate healthy donors and leukemia patients. Such a solution has the potential to improve the traditional diagnostics approaches with respect to the overall cost and time effort, in a label-free format, and restrictions of the complex data analysis. © 2020 American Chemical Society.},
      author_keywords={acute myeloid leukemia (AML); impedance cytometer; machine learning for data treatment; nanosensor; PBMCs; POC diagnostics},
      keywords={Diagnosis; Diseases; Machine learning, Acute myeloid leukemia; Cell classification; Human peripheral blood; Impedimetric detections; Microfluidic channel; Nanocapacitors; Output voltages; Peripheral blood, Blood, acute myeloid leukemia; human; monocyte; mononuclear cell; pilot study, Humans; Leukemia, Myeloid, Acute; Leukocytes, Mononuclear; Monocytes; Pilot Projects},
      correspondence_address1={Cuniberti, G.; Max Bergmann Center of Biomaterials, Budapesterstrasse 27, Germany; email: gianaurelio.cuniberti@tu-dresden.de; Baraban, L.; Max Bergmann Center of Biomaterials, Budapesterstrasse 27, Germany; email: l.baraban@hzdr.de},
      publisher={American Chemical Society},
      issn={15306984},
      coden={NALEF},
      pubmed_id={32786943},
      language={English},
      abbrev_source_title={Nano Lett.},
      document_type={Article},
      source={Scopus},
      }

  • Understanding the UV luminescence of zinc germanate: The role of native defects
    • J. Dolado, R. Martínez-Casado, P. Hidalgo, R. Gutierrez, A. Dianat, G. Cuniberti, F. Domínguez-Adame, E. Díaz, B. Méndez
    • Acta Materialia 196, 626-634 (2020)
    • DOI   Abstract  

      Achieving efficient and stable ultraviolet emission is a challenging goal in optoelectronic devices. Herein, we investigate the UV luminescence of zinc germanate Zn2GeO4 microwires by means of photoluminescence measurements as a function of temperature and excitation conditions. The emitted UV light is composed of two bands (a broad one and a narrow one) associated with the native defects structure. In addition, with the aid of density functional theory (DFT) calculations, the energy positions of the electronic levels related to native defects in Zn2GeO4 have been calculated. In particular, our results support that zinc interstitials are the responsible for the narrow UV band, which is, in turn, split into two components with different temperature dependence behaviour. The origin of the two components is explained on the basis of the particular location of Zni in the lattice and agrees with DFT calculations. Furthermore, a kinetic luminescence model is proposed to ascertain the temperature evolution of this UV emission. These results pave the way to exploit defect engineering in achieving functional optoelectronic devices to operate in the UV region. © 2020 Acta Materialia Inc.

      @ARTICLE{Dolado2020626,
      author={Dolado, J. and Martínez-Casado, R. and Hidalgo, P. and Gutierrez, R. and Dianat, A. and Cuniberti, G. and Domínguez-Adame, F. and Díaz, E. and Méndez, B.},
      title={Understanding the UV luminescence of zinc germanate: The role of native defects},
      journal={Acta Materialia},
      year={2020},
      volume={196},
      pages={626-634},
      doi={10.1016/j.actamat.2020.07.009},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087993125&doi=10.1016%2fj.actamat.2020.07.009&partnerID=40&md5=6a83cc7a1baa001b356c5a0bd1d238e9},
      affiliation={Departamento de Física de Materiales, Universidad Complutense de Madrid, Madrid, E-28040, Spain; Institute for Materials Science, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={Achieving efficient and stable ultraviolet emission is a challenging goal in optoelectronic devices. Herein, we investigate the UV luminescence of zinc germanate Zn2GeO4 microwires by means of photoluminescence measurements as a function of temperature and excitation conditions. The emitted UV light is composed of two bands (a broad one and a narrow one) associated with the native defects structure. In addition, with the aid of density functional theory (DFT) calculations, the energy positions of the electronic levels related to native defects in Zn2GeO4 have been calculated. In particular, our results support that zinc interstitials are the responsible for the narrow UV band, which is, in turn, split into two components with different temperature dependence behaviour. The origin of the two components is explained on the basis of the particular location of Zni in the lattice and agrees with DFT calculations. Furthermore, a kinetic luminescence model is proposed to ascertain the temperature evolution of this UV emission. These results pave the way to exploit defect engineering in achieving functional optoelectronic devices to operate in the UV region. © 2020 Acta Materialia Inc.},
      author_keywords={Density functional theory; Native defects; Photoluminescence; Ultraviolet emission; Zinc germanate},
      keywords={Defects; Luminescence; Optoelectronic devices; Temperature distribution; Zinc, Defect engineering; Excitation conditions; Luminescence models; Photoluminescence measurements; Temperature dependence; Temperature evolution; Ultraviolet emission; Zinc interstitials, Density functional theory},
      correspondence_address1={Méndez, B.; Departamento de Física de Materiales, Spain; email: bianchi@ucm.es},
      publisher={Acta Materialia Inc},
      issn={13596454},
      language={English},
      abbrev_source_title={Acta Mater},
      document_type={Article},
      source={Scopus},
      }

  • Field-induced interactions in magneto-active elastomers – A comparison of experiments and simulations
    • P. Metsch, H. Schmidt, D. Sindersberger, K. A Kalina, J. Brummund, G. K Auernhammer, G. J. Monkman, M. Kästner
    • Smart Materials and Structures 29, 085026 (2020)
    • DOI   Abstract  

      In this contribution, field-induced interactions of magnetizable particles embedded into a soft elastomer matrix are analyzed with regard to the resulting mechanical deformations. By comparing experiments for two-, three- and four-particle systems with the results of finite element simulations, a fully coupled continuum model for magneto-active elastomers is validated with the help of real data for the first time. The model under consideration permits the investigation of magneto-active elastomers with arbitrary particle distances, shapes and volume fractions as well as magnetic and mechanical properties of the individual constituents. It thus represents a basis for future studies on more complex, realistic systems. Our results show a very good agreement between experiments and numerical simulations – the deformation behavior of all systems is captured by the model qualitatively as well as quantitatively. Within a sensitivity analysis, the influence of the initial particle positions on the systems’ response is examined. Furthermore, a comparison of the full three-dimensional model with the often used, simplified two-dimensional approach shows the typical overestimation of resulting interactions in magneto-active elastomers. © 2020 The Author(s). Published by IOP Publishing Ltd.

      @ARTICLE{Metsch2020,
      author={Metsch, P. and Schmidt, H. and Sindersberger, D. and A Kalina, K. and Brummund, J. and K Auernhammer, G. and Monkman, G.J. and Kästner, M.},
      title={Field-induced interactions in magneto-active elastomers - A comparison of experiments and simulations},
      journal={Smart Materials and Structures},
      year={2020},
      volume={29},
      number={8},
      doi={10.1088/1361-665X/ab92dc},
      art_number={085026},
      note={cited By 8},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85089585983&doi=10.1088%2f1361-665X%2fab92dc&partnerID=40&md5=32b0144d5adaec5ef94ecbe186929794},
      affiliation={Institute of Solid Mechanics, Technische Universität Dresden, Dresden, 01062, Germany; Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany; Mechatronics Research Unit, OTH Regensburg, Regensburg, Germany; Leibniz-Institut für Polymerforschung Dresden E.V., Hohe Straße 6, 01069 Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, Germany},
      abstract={In this contribution, field-induced interactions of magnetizable particles embedded into a soft elastomer matrix are analyzed with regard to the resulting mechanical deformations. By comparing experiments for two-, three- and four-particle systems with the results of finite element simulations, a fully coupled continuum model for magneto-active elastomers is validated with the help of real data for the first time. The model under consideration permits the investigation of magneto-active elastomers with arbitrary particle distances, shapes and volume fractions as well as magnetic and mechanical properties of the individual constituents. It thus represents a basis for future studies on more complex, realistic systems. Our results show a very good agreement between experiments and numerical simulations - the deformation behavior of all systems is captured by the model qualitatively as well as quantitatively. Within a sensitivity analysis, the influence of the initial particle positions on the systems' response is examined. Furthermore, a comparison of the full three-dimensional model with the often used, simplified two-dimensional approach shows the typical overestimation of resulting interactions in magneto-active elastomers. © 2020 The Author(s). Published by IOP Publishing Ltd.},
      author_keywords={field-induced interactions; magneto-active elastomers; nonlinear finite element-method},
      keywords={Continuum mechanics; Deformation; Elastomers; Real time systems; Sensitivity analysis, Comparing experiments; Continuum Modeling; Deformation behavior; Finite element simulations; Four-particle systems; Full three-dimensional; Magnetic and mechanical properties; Mechanical deformation, Plastics},
      publisher={Institute of Physics Publishing},
      issn={09641726},
      coden={SMSTE},
      language={English},
      abbrev_source_title={Smart Mater Struct},
      document_type={Article},
      source={Scopus},
      }

  • Discovery, Crystal Growth, and Characterization of Garnet Eu2PbSb2Zn3O12
    • R. Morrow, M. I. Sturza, R. Ray, C. Himcinschi, J. Kern, P. Schlender, M. Richter, S. Wurmehl, B. Büchner
    • European Journal of Inorganic Chemistry 2020, 2512-2520 (2020)
    • DOI   Abstract  

      Single crystal specimens of previously unknown garnet Eu2PbSb2Zn3O12 were grown in a reactive PbO:PbF2 flux medium. The crystals were characterized by a combination of X-ray crystallography, magnetization measurements, and the optical techniques of Raman, photoluminescence, and UV/Vis spectroscopy. The material exhibits Van Vleck paramagnetism associated with the J = 0 state of Eu3+, which was possible to accurately fit to a theoretical model. Band structure calculations were performed and compared to the experimental band gap of 1.98 eV. The crystals demonstrate photoluminescence associated with the 4f 6 configuration of the Eu3+ ions sitting at the distorted 8-coordinate garnet A site. The title compound represents a unique quinary contribution to a relatively unexplored area of rare earth bearing garnet crystal chemistry. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

      @ARTICLE{Morrow20202512,
      author={Morrow, R. and Sturza, M.I. and Ray, R. and Himcinschi, C. and Kern, J. and Schlender, P. and Richter, M. and Wurmehl, S. and Büchner, B.},
      title={Discovery, Crystal Growth, and Characterization of Garnet Eu2PbSb2Zn3O12},
      journal={European Journal of Inorganic Chemistry},
      year={2020},
      volume={2020},
      number={26},
      pages={2512-2520},
      doi={10.1002/ejic.202000271},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85087171097&doi=10.1002%2fejic.202000271&partnerID=40&md5=871fb34e5836968fe3ee1ee7495913b4},
      affiliation={Leibniz Institute for Solid State and Materials Research Dresden IFW, Helmholtzstr. 20, Dresden, D-01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, D-01062, Germany; Institute of Theoretical Physics, TU Bergakademie Freiberg, Freiberg, D-09599, Germany; Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden, D-01062, Germany; Institut für Festkörperphysik, Technische Universität Dresden, Dresden, D-01069, Germany},
      abstract={Single crystal specimens of previously unknown garnet Eu2PbSb2Zn3O12 were grown in a reactive PbO:PbF2 flux medium. The crystals were characterized by a combination of X-ray crystallography, magnetization measurements, and the optical techniques of Raman, photoluminescence, and UV/Vis spectroscopy. The material exhibits Van Vleck paramagnetism associated with the J = 0 state of Eu3+, which was possible to accurately fit to a theoretical model. Band structure calculations were performed and compared to the experimental band gap of 1.98 eV. The crystals demonstrate photoluminescence associated with the 4f 6 configuration of the Eu3+ ions sitting at the distorted 8-coordinate garnet A site. The title compound represents a unique quinary contribution to a relatively unexplored area of rare earth bearing garnet crystal chemistry. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.},
      author_keywords={Crystal growth; Garnet; Magnetic properties; Photoluminescence; Solid State Chemistry},
      correspondence_address1={Morrow, R.; Leibniz Institute for Solid State and Materials Research Dresden IFW, Helmholtzstr. 20, Germany; email: r.c.morrow@ifw-dresden.de},
      publisher={Wiley-VCH Verlag},
      issn={14341948},
      coden={EJICF},
      language={English},
      abbrev_source_title={Eur. J. Inorg. Chem.},
      document_type={Article},
      source={Scopus},
      }

  • First-principles calculation of shift current in chalcopyrite semiconductor ZnSnP2
    • B. Sadhukhan, Y. Zhang, R. Ray, J. Van Den Brink
    • Physical Review Materials 4, 064602 (2020)
    • DOI   Abstract  

      The bulk photovoltaic effect generates intrinsic photocurrents in materials without inversion symmetry. Shift current is one of the bulk photovoltaic phenomena related to the Berry phase of the constituting electronic bands: photoexcited carriers coherently shift in real space due to the difference in the Berry connection between the valence and conduction bands. Ferroelectric semiconductors and Weyl semimetals are known to exhibit such nonlinear optical phenomena. Here we consider the chalcopyrite semiconductor ZnSnP2, which lacks inversion symmetry, and calculate the shift-current conductivity. We find that the magnitude of the shift current is comparable to the recently measured values on other ferroelectric semiconductors and an order of magnitude larger than bismuth ferrite. The peak response for both optical and shift-current conductivity, which mainly comes from P-3p and Sn-5p orbitals, is several eV above the band gap. © 2020 American Physical Society.

      @ARTICLE{Sadhukhan2020,
      author={Sadhukhan, B. and Zhang, Y. and Ray, R. and Van Den Brink, J.},
      title={First-principles calculation of shift current in chalcopyrite semiconductor ZnSnP2},
      journal={Physical Review Materials},
      year={2020},
      volume={4},
      number={6},
      doi={10.1103/PhysRevMaterials.4.064602},
      art_number={064602},
      note={cited By 13},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85088555947&doi=10.1103%2fPhysRevMaterials.4.064602&partnerID=40&md5=ca0d690022a75dc141859bb33a6c6e51},
      affiliation={Leibniz Institute for Solid State and Materials Research IFW Dresden, Helmholtzstrasse 20, Dresden, 01069, Germany; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Max Planck Institute for Chemical Physics of Solids, Dresden, 01187, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, D-01062, Germany},
      abstract={The bulk photovoltaic effect generates intrinsic photocurrents in materials without inversion symmetry. Shift current is one of the bulk photovoltaic phenomena related to the Berry phase of the constituting electronic bands: photoexcited carriers coherently shift in real space due to the difference in the Berry connection between the valence and conduction bands. Ferroelectric semiconductors and Weyl semimetals are known to exhibit such nonlinear optical phenomena. Here we consider the chalcopyrite semiconductor ZnSnP2, which lacks inversion symmetry, and calculate the shift-current conductivity. We find that the magnitude of the shift current is comparable to the recently measured values on other ferroelectric semiconductors and an order of magnitude larger than bismuth ferrite. The peak response for both optical and shift-current conductivity, which mainly comes from P-3p and Sn-5p orbitals, is several eV above the band gap. © 2020 American Physical Society.},
      keywords={Copper compounds; Energy gap; Ferrite; Ferroelectricity; Fruits; Photovoltaic effects, Bismuth ferrites; Chalcopyrite semiconductor; Current conductivity; Ferroelectric semiconductors; First-principles calculation; Inversion symmetry; Non-linear optical; Photoexcited carriers, Calculations},
      publisher={American Physical Society},
      issn={24759953},
      language={English},
      abbrev_source_title={Physic. Rev. Mat.},
      document_type={Article},
      source={Scopus},
      }

  • Phase-field modeling of crack branching and deflection in heterogeneous media
    • A. C. Hansen-Dörr, F. Dammaß, R. de Borst, M. Kästner
    • Engineering Fracture Mechanics 232, 107004 (2020)
    • DOI   Abstract  

      This contribution presents a diffuse framework for modeling cracks in heterogeneous media. Interfaces are depicted by static phase-fields. This concept allows the use of non-conforming meshes. Another phase-field is used to describe the crack evolution in a regularized manner. The interface modeling implements two combined approaches. Firstly, a method from the literature is extended where the interface is incorporated by a local reduction of the fracture toughness. Secondly, variations of the elastic properties across the interface are enabled by approximating the abrupt change between two adjacent subdomains using a hyperbolic tangent function, which alters the elastic material parameters accordingly. The approach is validated qualitatively by means of crack patterns and quantitatively with respect to critical energy release rates with fundamental analytical results from Linear Elastic Fracture Mechanics, where a crack impinges an arbitrarily oriented interface and either branches, gets deflected or experiences no interfacial influence. The model is particularly relevant for phase-field analyses in heterogeneous, possibly complex-shaped solids, where cohesive failure in the constituent materials as well as adhesive failure at interfaces and its quantification play a role. © 2020 Elsevier Ltd

      @ARTICLE{Hansen-Dörr2020,
      author={Hansen-Dörr, A.C. and Dammaß, F. and de Borst, R. and Kästner, M.},
      title={Phase-field modeling of crack branching and deflection in heterogeneous media},
      journal={Engineering Fracture Mechanics},
      year={2020},
      volume={232},
      doi={10.1016/j.engfracmech.2020.107004},
      art_number={107004},
      note={cited By 25},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084230485&doi=10.1016%2fj.engfracmech.2020.107004&partnerID=40&md5=3db16b36006c74a5d0b40cd35c87af1c},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, 01062, Germany; University of Sheffield, Department of Civil and Structural Engineering, Mappin Street, Sir Frederick Mappin Building, Sheffield, S1 3JD, United Kingdom; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={This contribution presents a diffuse framework for modeling cracks in heterogeneous media. Interfaces are depicted by static phase-fields. This concept allows the use of non-conforming meshes. Another phase-field is used to describe the crack evolution in a regularized manner. The interface modeling implements two combined approaches. Firstly, a method from the literature is extended where the interface is incorporated by a local reduction of the fracture toughness. Secondly, variations of the elastic properties across the interface are enabled by approximating the abrupt change between two adjacent subdomains using a hyperbolic tangent function, which alters the elastic material parameters accordingly. The approach is validated qualitatively by means of crack patterns and quantitatively with respect to critical energy release rates with fundamental analytical results from Linear Elastic Fracture Mechanics, where a crack impinges an arbitrarily oriented interface and either branches, gets deflected or experiences no interfacial influence. The model is particularly relevant for phase-field analyses in heterogeneous, possibly complex-shaped solids, where cohesive failure in the constituent materials as well as adhesive failure at interfaces and its quantification play a role. © 2020 Elsevier Ltd},
      author_keywords={Adhesive failure; Brittle fracture; Diffuse modeling framework; Heterogeneity; Phase-field modeling},
      keywords={Adhesives; Brittle fracture; Elasticity; Fracture mechanics; Fracture toughness; Hyperbolic functions; Phase interfaces, Adhesive failure; Crack branching; Cracks deflections; Diffuse modeling framework; Diffuse models; Heterogeneity; Heterogeneous media; Modelling framework; Phase field models; Phase fields, Cracks},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={00137944},
      coden={EFMEA},
      language={English},
      abbrev_source_title={Eng. Fract. Mech.},
      document_type={Article},
      source={Scopus},
      }

  • Towards synthetic neural networks: Can artificial electrochemical neurons be coupled with artificial memristive synapses?
    • E. Wlaźlak, D. Przyczyna, R. Gutierrez, G. Cuniberti, K. Szaciłowski
    • Japanese Journal of Applied Physics 59, SI0801 (2020)
    • DOI   Abstract  

      The enormous amount of data generated nowadays worldwide is increasingly triggering the search for unconventional and more efficient ways of processing and classifying information, eventually able to transcend the conventional von Neumann-Turing computational central dogma. It is, therefore, greatly appealing to draw inspiration from less conventional but computationally more powerful systems such as the neural architecture of the human brain. This neuromorphic route has the potential to become one of the most influential and long-lasting paradigms in the field of unconventional computing. Memristive and the recently proposed memfractive systems have been shown to display basic features of neural systems such as synaptic-like plasticity and memory features, so that they may offer a diverse playground to implement synaptic connections. In this review, we address various material-based strategies of implementing unconventional computing hardware: (i) electrochemical oscillators based on liquid metals and (ii) mem-devices exploiting Schottky barrier modulation in polycrystalline and disordered structures made of oxide or perovskite-type semiconductors. Both items (i) and (ii) build the two pillars of neuromimetic computing devices, which we will denote as synthetic neural networks. We expect that the current review will be of great interest for scientists aiming at bridging unconventional computing strategies with specific materials-based platforms. © 2020 The Japan Society of Applied Physics.

      @ARTICLE{Wlaźlak2020,
      author={Wlaźlak, E. and Przyczyna, D. and Gutierrez, R. and Cuniberti, G. and Szaciłowski, K.},
      title={Towards synthetic neural networks: Can artificial electrochemical neurons be coupled with artificial memristive synapses?},
      journal={Japanese Journal of Applied Physics},
      year={2020},
      volume={59},
      number={SI},
      doi={10.35848/1347-4065/ab7e11},
      art_number={SI0801},
      note={cited By 6},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85083111248&doi=10.35848%2f1347-4065%2fab7e11&partnerID=40&md5=031907c94341c99259665f25513267b4},
      affiliation={Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. Mickiewicza 30, Kraków, 30-059, Poland; Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, Kraków, 30-059, Poland; Institute for Materials Science, Max Bergmann Center of Biomaterials, Dresden University of Technology, Dresden, D-01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, D-01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, D-01062, Germany},
      abstract={The enormous amount of data generated nowadays worldwide is increasingly triggering the search for unconventional and more efficient ways of processing and classifying information, eventually able to transcend the conventional von Neumann-Turing computational central dogma. It is, therefore, greatly appealing to draw inspiration from less conventional but computationally more powerful systems such as the neural architecture of the human brain. This neuromorphic route has the potential to become one of the most influential and long-lasting paradigms in the field of unconventional computing. Memristive and the recently proposed memfractive systems have been shown to display basic features of neural systems such as synaptic-like plasticity and memory features, so that they may offer a diverse playground to implement synaptic connections. In this review, we address various material-based strategies of implementing unconventional computing hardware: (i) electrochemical oscillators based on liquid metals and (ii) mem-devices exploiting Schottky barrier modulation in polycrystalline and disordered structures made of oxide or perovskite-type semiconductors. Both items (i) and (ii) build the two pillars of neuromimetic computing devices, which we will denote as synthetic neural networks. We expect that the current review will be of great interest for scientists aiming at bridging unconventional computing strategies with specific materials-based platforms. © 2020 The Japan Society of Applied Physics.},
      keywords={Perovskite; Schottky barrier diodes, Computing devices; Disordered structures; Electrochemical oscillators; Neural architectures; Specific materials; Synaptic connections; Synthetic neural network; Unconventional computing, Classification (of information)},
      publisher={Institute of Physics Publishing},
      issn={00214922},
      language={English},
      abbrev_source_title={Jpn. J. Appl. Phys.},
      document_type={Article},
      source={Scopus},
      }

  • A macroscopic model for magnetorheological elastomers based on microscopic simulations
    • K. A. Kalina, P. Metsch, J. Brummund, M. Kästner
    • International Journal of Solids and Structures 193-194, 200-212 (2020)
    • DOI   Abstract  

      In this contribution, we present a novel proceeding for the development of a suitable macroscopic model for magneto-active composites. Based on a general continuum formulation of the coupled magneto-mechanical boundary value problem, valid for finite strains, a microscopic modeling approach is applied within a computational homogenization scheme. The calculated effective magneto-mechanical response of the composite system is used to identify the parameters of the macroscopic model. The merit of this strategy is the identification of the model fitting parameters independent of any macroscopic sample geometry. Furthermore, it facilitates the generation of large databases consisting of multiple load cases without performing expensive experiments. This strategy is applied for several microstructures with random particle distributions, where two-dimensional plane strain problems in the linear magnetization regime are considered for now. Finally, the magnetostrictive behavior of a macroscopic magneto-rheological elastomer sample is simulated for different sample geometries and underlying microstructures. © 2020

      @ARTICLE{Kalina2020200,
      author={Kalina, K.A. and Metsch, P. and Brummund, J. and Kästner, M.},
      title={A macroscopic model for magnetorheological elastomers based on microscopic simulations},
      journal={International Journal of Solids and Structures},
      year={2020},
      volume={193-194},
      pages={200-212},
      doi={10.1016/j.ijsolstr.2020.02.028},
      note={cited By 24},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079865472&doi=10.1016%2fj.ijsolstr.2020.02.028&partnerID=40&md5=5535f2086ae130458ed33aeb1aef70f1},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={In this contribution, we present a novel proceeding for the development of a suitable macroscopic model for magneto-active composites. Based on a general continuum formulation of the coupled magneto-mechanical boundary value problem, valid for finite strains, a microscopic modeling approach is applied within a computational homogenization scheme. The calculated effective magneto-mechanical response of the composite system is used to identify the parameters of the macroscopic model. The merit of this strategy is the identification of the model fitting parameters independent of any macroscopic sample geometry. Furthermore, it facilitates the generation of large databases consisting of multiple load cases without performing expensive experiments. This strategy is applied for several microstructures with random particle distributions, where two-dimensional plane strain problems in the linear magnetization regime are considered for now. Finally, the magnetostrictive behavior of a macroscopic magneto-rheological elastomer sample is simulated for different sample geometries and underlying microstructures. © 2020},
      author_keywords={Macro-model; Magneto-mechanical coupling; Magnetorheological elastomers; Parameter identification},
      keywords={Boundary value problems; Continuum mechanics; Elastomers; Identification (control systems); Microstructure; Plastics; Strain, Computational homogenization; Continuum formulation; Macro model; Magneto-rheological elastomers; Magnetomechanical couplings; Magnetostrictive behavior; Mechanical boundaries; Microscopic simulation, Parameter estimation},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={00207683},
      language={English},
      abbrev_source_title={Int. J. Solids Struct.},
      document_type={Article},
      source={Scopus},
      }

  • Self-Assembly of Nanovoids in Si Microcrystals Epitaxially Grown on Deeply Patterned Substrates
    • A. Barzaghi, S. Firoozabadi, M. Salvalaglio, R. Bergamaschini, A. Ballabio, A. Beyer, M. Albani, J. Valente, A. Voigt, D. J. Paul, L. Miglio, F. Montalenti, K. Volz, G. Isella
    • Crystal Growth and Design 20, 2914-2920 (2020)
    • DOI   Abstract  

      We present an experimental and theoretical analysis of the formation of nanovoids within Si microcrystals epitaxially grown on Si patterned substrates. The growth conditions leading to the nucleation of nanovoids have been highlighted, and the roles played by the deposition rate, substrate temperature, and substrate pattern geometry are identified. By combining various scanning and transmission electron microscopy techniques, it has been possible to link the appearance pits of a few hundred nanometer width at the microcrystal surface with the formation of nanovoids within the crystal volume. A phase-field model, including surface diffusion and the flux of incoming material with shadowing effects, reproduces the qualitative features of the nanovoid formation thereby opening new perspectives for the bottom-up fabrication of 3D semiconductors microstructures. © 2020 American Chemical Society.

      @ARTICLE{Barzaghi20202914,
      author={Barzaghi, A. and Firoozabadi, S. and Salvalaglio, M. and Bergamaschini, R. and Ballabio, A. and Beyer, A. and Albani, M. and Valente, J. and Voigt, A. and Paul, D.J. and Miglio, L. and Montalenti, F. and Volz, K. and Isella, G.},
      title={Self-Assembly of Nanovoids in Si Microcrystals Epitaxially Grown on Deeply Patterned Substrates},
      journal={Crystal Growth and Design},
      year={2020},
      volume={20},
      number={5},
      pages={2914-2920},
      doi={10.1021/acs.cgd.9b01312},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084742273&doi=10.1021%2facs.cgd.9b01312&partnerID=40&md5=0b09c2a902831704aa762a57adcbd09d},
      affiliation={L-NESS, Dipartimento di Fisica, Politecnico di Milano, Via Anzani 42, Como, 22100, Italy; Materials Science Center, Faculty of Physics, Philipps-Universität Marburg, Hans-Meerweinstraße 6, Marburg, 35032, Germany; Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; L-NESS and Dipartimento di Scienza Dei Materiali, Università di Milano-Bicocca, Via R. Cozzi 55, Milano, I-20125, Italy; James Watt School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, G12 8LT, United Kingdom},
      abstract={We present an experimental and theoretical analysis of the formation of nanovoids within Si microcrystals epitaxially grown on Si patterned substrates. The growth conditions leading to the nucleation of nanovoids have been highlighted, and the roles played by the deposition rate, substrate temperature, and substrate pattern geometry are identified. By combining various scanning and transmission electron microscopy techniques, it has been possible to link the appearance pits of a few hundred nanometer width at the microcrystal surface with the formation of nanovoids within the crystal volume. A phase-field model, including surface diffusion and the flux of incoming material with shadowing effects, reproduces the qualitative features of the nanovoid formation thereby opening new perspectives for the bottom-up fabrication of 3D semiconductors microstructures. © 2020 American Chemical Society.},
      keywords={Deposition rates; High resolution transmission electron microscopy; Microcrystals; Scanning electron microscopy; Self assembly; Silicon, Bottom-up fabrication; Patterned substrates; Phase field models; Qualitative features; Scanning and transmission electron microscopy; Shadowing effects; Substrate pattern; Substrate temperature, Substrates},
      correspondence_address1={Isella, G.; L-NESS, Via Anzani 42, Italy; email: giovanni.isella@polimi.it},
      publisher={American Chemical Society},
      issn={15287483},
      coden={CGDEF},
      language={English},
      abbrev_source_title={Cryst. Growth Des.},
      document_type={Article},
      source={Scopus},
      }

  • A Phase Field Approach to Trabecular Bone Remodeling
    • S. Aland, F. Stenger, R. Müller, A. Deutsch, A. Voigt
    • Frontiers in Applied Mathematics and Statistics 6, 12 (2020)
    • DOI   Abstract  

      We introduce a continuous modeling approach which combines elastic response of the trabecular bone structure with the concentration of signaling molecules within the bone and a mechanism for concentration dependent local bone formation and resorption. In an abstract setting bone can be considered as a shape changing structure. For similar problems in materials science phase field approximations have been established as an efficient computational tool. We adapt such an approach for trabecular bone remodeling. It allows for a smooth representation of the trabecular bone structure and drastically reduces computational costs if compared with traditional micro finite element approaches. We demonstrate the advantage of the approach within a minimal model. We quantitatively compare the results with established micro finite element approaches on simple geometries and consider the bone morphology within a bone segment obtained from μCT data of a sheep vertebra with realistic parameters. © Copyright © 2020 Aland, Stenger, Müller, Deutsch and Voigt.

      @ARTICLE{Aland2020,
      author={Aland, S. and Stenger, F. and Müller, R. and Deutsch, A. and Voigt, A.},
      title={A Phase Field Approach to Trabecular Bone Remodeling},
      journal={Frontiers in Applied Mathematics and Statistics},
      year={2020},
      volume={6},
      doi={10.3389/fams.2020.00012},
      art_number={12},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85085109851&doi=10.3389%2ffams.2020.00012&partnerID=40&md5=95c55f5ab52fb9e4217709eda51fd2a7},
      affiliation={Faculty of Informatics/Mathematics, HTW Dresden, Dresden, Germany; Institut für Wissenschaftliches Rechnen, TU Dresden, Dresden, Germany; Center for Information Services and High Performance Computing, TU Dresden, Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), Dresden, Germany; Center for Systems Biology Dresden (CSBD), Dresden, Germany},
      abstract={We introduce a continuous modeling approach which combines elastic response of the trabecular bone structure with the concentration of signaling molecules within the bone and a mechanism for concentration dependent local bone formation and resorption. In an abstract setting bone can be considered as a shape changing structure. For similar problems in materials science phase field approximations have been established as an efficient computational tool. We adapt such an approach for trabecular bone remodeling. It allows for a smooth representation of the trabecular bone structure and drastically reduces computational costs if compared with traditional micro finite element approaches. We demonstrate the advantage of the approach within a minimal model. We quantitatively compare the results with established micro finite element approaches on simple geometries and consider the bone morphology within a bone segment obtained from μCT data of a sheep vertebra with realistic parameters. © Copyright © 2020 Aland, Stenger, Müller, Deutsch and Voigt.},
      author_keywords={bone remodeling; mechanosensing; phase-field; topology optimization; trabecular bone},
      correspondence_address1={Aland, S.; Faculty of Informatics/Mathematics, Germany; email: sebastian.aland@htw-dresden.de},
      publisher={Frontiers Media S.A.},
      issn={22974687},
      language={English},
      abbrev_source_title={Front Appl Math Stat},
      document_type={Article},
      source={Scopus},
      }

  • Properties of surface Landau-de GennesQ-tensor models
    • M. Nestler, I. Nitschke, H. Löwen, A. Voigt
    • Soft Matter 16, 4032-4042 (2020)
    • DOI   Abstract  

      Uniaxial nematic liquid crystals whose molecular orientation is subjected to tangential anchoring on a curved surface offer a non trivial interplay between the geometry and the topology of the surface and the orientational degree of freedom. We consider a general thin film limit of a Landau-de GennesQ-tensor model which retains the characteristics of the 3D model. From this, previously proposed surface models follow as special cases. We compare fundamental properties, such as the alignment of the orientational degrees of freedom with principle curvature lines, order parameter symmetry and phase transition type for these models, and suggest experiments to identify suitable model assumptions. © The Royal Society of Chemistry 2020.

      @ARTICLE{Nestler20204032,
      author={Nestler, M. and Nitschke, I. and Löwen, H. and Voigt, A.},
      title={Properties of surface Landau-de GennesQ-tensor models},
      journal={Soft Matter},
      year={2020},
      volume={16},
      number={16},
      pages={4032-4042},
      doi={10.1039/c9sm02475a},
      note={cited By 8},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084175201&doi=10.1039%2fc9sm02475a&partnerID=40&md5=0a389dc8161a9edb5f419b5a7b017256},
      affiliation={Institut für Wissenschaftliches Rechnen, Technische Universität Dresden, Dresden, 01062, Germany; Institut für Theoretische Physik II - Soft Matter, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, 40225, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Center for Systems Biology Dresden (CSBD), Pfotenhauerstr. 108, Dresden, 01307, Germany},
      abstract={Uniaxial nematic liquid crystals whose molecular orientation is subjected to tangential anchoring on a curved surface offer a non trivial interplay between the geometry and the topology of the surface and the orientational degree of freedom. We consider a general thin film limit of a Landau-de GennesQ-tensor model which retains the characteristics of the 3D model. From this, previously proposed surface models follow as special cases. We compare fundamental properties, such as the alignment of the orientational degrees of freedom with principle curvature lines, order parameter symmetry and phase transition type for these models, and suggest experiments to identify suitable model assumptions. © The Royal Society of Chemistry 2020.},
      keywords={3D modeling; Crystal orientation; Molecular orientation; Nematic liquid crystals; Tensors, Curved surfaces; Degree of freedom; Fundamental properties; Model assumptions; Non-trivial; Order parameter symmetry; Surface models; Tensor model, Degrees of freedom (mechanics)},
      correspondence_address1={Nestler, M.; Institut für Wissenschaftliches Rechnen, Germany; email: michael.nestler@tu-dresden.de},
      publisher={Royal Society of Chemistry},
      issn={1744683X},
      coden={SMOAB},
      pubmed_id={32270809},
      language={English},
      abbrev_source_title={Soft Matter},
      document_type={Article},
      source={Scopus},
      }

  • Bending rigidities and universality of flexural modes in 2D crystals
    • A. Croy
    • JPhys Materials 3, 02LT03 (2020)
    • DOI   Abstract  

      The existence of flexural modes with a quadratic phonon-dispersion is a distinguishing property of two-dimensional materials and has important consequences for their properties. Here, we deduce theoretically within the harmonic approximation the conditions for which orthotropic two-dimensional materials display a flexural mode. Further, we derive formulae for the calculation of the corresponding bending rigidities using the equilibrium structure and the second-order force constants as input. This completes the description of the elasticity of 2D crystals. Our findings are exemplarily validated by ab initio calculations of the phonon dispersions of four representative materials. © 2020 The Author(s). Published by IOP Publishing Ltd.

      @ARTICLE{Croy2020,
      author={Croy, A.},
      title={Bending rigidities and universality of flexural modes in 2D crystals},
      journal={JPhys Materials},
      year={2020},
      volume={3},
      number={2},
      doi={10.1088/2515-7639/ab8271},
      art_number={02LT03},
      note={cited By 5},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85099776349&doi=10.1088%2f2515-7639%2fab8271&partnerID=40&md5=7b8fdca9be65c6c205684eea27015b9c},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01069, Germany},
      abstract={The existence of flexural modes with a quadratic phonon-dispersion is a distinguishing property of two-dimensional materials and has important consequences for their properties. Here, we deduce theoretically within the harmonic approximation the conditions for which orthotropic two-dimensional materials display a flexural mode. Further, we derive formulae for the calculation of the corresponding bending rigidities using the equilibrium structure and the second-order force constants as input. This completes the description of the elasticity of 2D crystals. Our findings are exemplarily validated by ab initio calculations of the phonon dispersions of four representative materials. © 2020 The Author(s). Published by IOP Publishing Ltd.},
      author_keywords={2D Mmterials; Bending rigidity; Phonon dispersion; Strain engineering},
      keywords={Acoustic dispersion; Crystals; Dispersions; Equilibrium constants; Phonons; Rigidity, Ab initio calculations; Bending rigidity; Equilibrium structures; Flexural modes; Force constants; Harmonic approximation; Phonon dispersions; Two-dimensional materials, Calculations},
      correspondence_address1={Croy, A.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: alexander.croy@tu-dresden.de},
      publisher={IOP Publishing Ltd},
      issn={25157639},
      language={English},
      abbrev_source_title={JPhys mater.},
      document_type={Article},
      source={Scopus},
      }

  • A coarse-grained phase-field crystal model of plastic motion
    • M. Salvalaglio, L. Angheluta, Z. -F. Huang, A. Voigt, K. R. Elder, J. Viñals
    • Journal of the Mechanics and Physics of Solids 137, 103856 (2020)
    • DOI   Abstract  

      The phase-field crystal model in an amplitude equation approximation is shown to provide an accurate description of the deformation field in defected crystalline structures, as well as of dislocation motion. We analyze in detail stress regularization at a dislocation core given by the model, and show how the Burgers vector density can be directly computed from the topological singularities of the phase-field amplitudes. Distortions arising from these amplitudes are then supplemented with non-singular displacements to enforce mechanical equilibrium. This allows for a consistent separation of plastic and elastic time scales in this framework. A finite element method is introduced to solve the combined amplitude and elasticity equations, which is applied to a few prototypical configurations in two spatial dimensions for a crystal of triangular lattice symmetry: i) the stress field induced by an edge dislocation with an analysis of how the amplitude equation regularizes stresses near the dislocation core, ii) the motion of a dislocation dipole as a result of its internal interaction, and iii) the shrinkage of a rotated grain. We compare our results with those given by other extensions of classical elasticity theory, such as strain-gradient elasticity and methods based on the smoothing of Burgers vector densities near defect cores. © 2019

      @ARTICLE{Salvalaglio2020,
      author={Salvalaglio, M. and Angheluta, L. and Huang, Z.-F. and Voigt, A. and Elder, K.R. and Viñals, J.},
      title={A coarse-grained phase-field crystal model of plastic motion},
      journal={Journal of the Mechanics and Physics of Solids},
      year={2020},
      volume={137},
      doi={10.1016/j.jmps.2019.103856},
      art_number={103856},
      note={cited By 23},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077304464&doi=10.1016%2fj.jmps.2019.103856&partnerID=40&md5=ab2a8ab2bb9b8945ab51e0f0df83aad5},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Hong Kong Institute for Advanced Studies and Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong SAR, China; PoreLab, The Njord Centre, Department of Physics, University of Oslo, P. O. Box 1048, Oslo, 0316, Norway; Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, United States; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Department of Physics, Oakland University, Rochester, MI 48309, United States; School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455, United States},
      abstract={The phase-field crystal model in an amplitude equation approximation is shown to provide an accurate description of the deformation field in defected crystalline structures, as well as of dislocation motion. We analyze in detail stress regularization at a dislocation core given by the model, and show how the Burgers vector density can be directly computed from the topological singularities of the phase-field amplitudes. Distortions arising from these amplitudes are then supplemented with non-singular displacements to enforce mechanical equilibrium. This allows for a consistent separation of plastic and elastic time scales in this framework. A finite element method is introduced to solve the combined amplitude and elasticity equations, which is applied to a few prototypical configurations in two spatial dimensions for a crystal of triangular lattice symmetry: i) the stress field induced by an edge dislocation with an analysis of how the amplitude equation regularizes stresses near the dislocation core, ii) the motion of a dislocation dipole as a result of its internal interaction, and iii) the shrinkage of a rotated grain. We compare our results with those given by other extensions of classical elasticity theory, such as strain-gradient elasticity and methods based on the smoothing of Burgers vector densities near defect cores. © 2019},
      author_keywords={coarse-graining; crystal plasticity; dislocation motion; finite element method; phase-field crystal},
      keywords={Burgers vector; Edge dislocations; Elasticity; Finite element method; Shrinkage; Topology, Coarse Graining; Crystal plasticity; Crystalline structure; Dislocation motion; Mechanical equilibrium; Phase field crystal model; Phase-field crystals; Strain gradient elasticity, Crystal symmetry},
      correspondence_address1={Salvalaglio, M.; Technische Universität DresdenGermany; email: marco.salvalaglio@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={00225096},
      coden={JMPSA},
      language={English},
      abbrev_source_title={J Mech Phys Solids},
      document_type={Article},
      source={Scopus},
      }

  • Magnetically induced/enhanced coarsening in thin films
    • R. Backofen, A. Voigt
    • Physical Review Materials 4, 023404 (2020)
    • DOI   Abstract  

      External magnetic fields influence the microstructure of polycrystalline materials. We explore the influence of strong external magnetic fields on the long time scaling of grain size during coarsening in thin films with an extended phase-field-crystal model. Additionally, the change of various geometrical and topological properties is studied. In a situation which leads to stagnation, an applied external magnetic field can induce further grain growth. The induced driving force due to the magnetic anisotropy defines the magnetic influence of the external magnetic field. Different scaling regimes are identified dependent on the magnetization. At the beginning, the scaling exponent increases with the strength of the magnetization. Later, when the texture becomes dominated by grains preferably aligned with the external magnetic field, the scaling exponent becomes independent of the strength of the magnetization or stagnation occurs. We discuss how the magnetic influence change the effect of retarding or pinning forces, which are known to influence the scaling exponent. We further study the influence of the magnetic field on the grain size distribution (GSD), next-neighbor distribution (NND) as well as grain shape and orientation. If possible, we compare our predictions with experimental findings. © 2020 American Physical Society.

      @ARTICLE{Backofen2020,
      author={Backofen, R. and Voigt, A.},
      title={Magnetically induced/enhanced coarsening in thin films},
      journal={Physical Review Materials},
      year={2020},
      volume={4},
      number={2},
      doi={10.1103/PhysRevMaterials.4.023404},
      art_number={023404},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082656985&doi=10.1103%2fPhysRevMaterials.4.023404&partnerID=40&md5=b36f1f6e1ae918421394ca249d6706d3},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Dresden, 01062, Germany},
      abstract={External magnetic fields influence the microstructure of polycrystalline materials. We explore the influence of strong external magnetic fields on the long time scaling of grain size during coarsening in thin films with an extended phase-field-crystal model. Additionally, the change of various geometrical and topological properties is studied. In a situation which leads to stagnation, an applied external magnetic field can induce further grain growth. The induced driving force due to the magnetic anisotropy defines the magnetic influence of the external magnetic field. Different scaling regimes are identified dependent on the magnetization. At the beginning, the scaling exponent increases with the strength of the magnetization. Later, when the texture becomes dominated by grains preferably aligned with the external magnetic field, the scaling exponent becomes independent of the strength of the magnetization or stagnation occurs. We discuss how the magnetic influence change the effect of retarding or pinning forces, which are known to influence the scaling exponent. We further study the influence of the magnetic field on the grain size distribution (GSD), next-neighbor distribution (NND) as well as grain shape and orientation. If possible, we compare our predictions with experimental findings. © 2020 American Physical Society.},
      keywords={Coarsening; Grain growth; Grain size and shape; Magnetic fields; Magnetization; Ostwald ripening; Polycrystalline materials; Scaling laws; Textures; Thin films; Topology, External magnetic field; Grain size distribution; Magnetic influence; Phase field crystal model; Pinning forces; Scaling exponent; Scaling regimes; Topological properties, Magnetic anisotropy},
      publisher={American Physical Society},
      issn={24759953},
      language={English},
      abbrev_source_title={Physic. Rev. Mat.},
      document_type={Article},
      source={Scopus},
      }

  • ProMAD: Semiquantitative densitometric measurement of protein microarrays
    • A. Jaeschke, H. Eckert, L. J. Bray
    • BMC Bioinformatics 21, 72 (2020)
    • DOI   Abstract  

      Background: Protein microarrays are a versatile and widely used tool for analyzing complex protein mixtures. Membrane arrays utilize antibodies which are captured on a membrane to specifically immobilize several proteins of interest at once. Using detection antibodies, the bound protein-Antibody-complex is converted into visual signals, which can be quantified using densitometry. The reliability of such densitometric assessments depends on a variety of factors, not only sample preparation and the choice of acquisition device but also the selected analysis software and the algorithms used for readout and processing data. Currently available software packages use a single image of a membrane at an optimal exposure time selected for that specific experimental framework. This selection is based on a user’s best guess and is subject to inter-user variability or the acquisition device algorithm. With modern image acquisition systems proving the capacity to collect signal development over time, this information can be used to improve densitometric measurements. Here we introduce proMAD, a toolkit for protein microarray analysis providing a novel systemic approach for the quantification of membrane arrays based on the kinetics of the analytical reaction. Results: Briefly, our toolkit ensures an exact membrane alignment, utilizing basic computer vision techniques. It also provides a stable method to estimate the background light level. Finally, we model the light production over time, utilizing the knowledge about the reaction kinetics of the underlying horseradish peroxidase-based signal detection method. Conclusion: proMAD incorporates the reaction kinetics of the enzyme to model the signal development over time for each membrane creating an individual, self-referencing concept. Variations of membranes within a given experimental set up can be accounted for, allowing for a better comparison of such. While the open-source library can be implemented in existing workflows and used for highly user-Tailored analytic setups, the web application, on the other hand, provides easy platform-independent access to the core algorithm to a wide range of researchers. proMAD’s inherent flexibility has the potential to cover a wide range of use-cases and enables the automation of data analytic tasks. © 2020 The Author(s).

      @ARTICLE{Jaeschke2020,
      author={Jaeschke, A. and Eckert, H. and Bray, L.J.},
      title={ProMAD: Semiquantitative densitometric measurement of protein microarrays},
      journal={BMC Bioinformatics},
      year={2020},
      volume={21},
      number={1},
      doi={10.1186/s12859-020-3402-4},
      art_number={72},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85080938471&doi=10.1186%2fs12859-020-3402-4&partnerID=40&md5=b269ead70a101f1aab0af692f5e975aa},
      affiliation={Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD 4059, Australia; School of Mechanical, Medical and Process Engineering, Science and Engineering Faculty, Queensland University of Technology, Kelvin Grove, QLD 4059, Australia; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, Germany},
      abstract={Background: Protein microarrays are a versatile and widely used tool for analyzing complex protein mixtures. Membrane arrays utilize antibodies which are captured on a membrane to specifically immobilize several proteins of interest at once. Using detection antibodies, the bound protein-Antibody-complex is converted into visual signals, which can be quantified using densitometry. The reliability of such densitometric assessments depends on a variety of factors, not only sample preparation and the choice of acquisition device but also the selected analysis software and the algorithms used for readout and processing data. Currently available software packages use a single image of a membrane at an optimal exposure time selected for that specific experimental framework. This selection is based on a user's best guess and is subject to inter-user variability or the acquisition device algorithm. With modern image acquisition systems proving the capacity to collect signal development over time, this information can be used to improve densitometric measurements. Here we introduce proMAD, a toolkit for protein microarray analysis providing a novel systemic approach for the quantification of membrane arrays based on the kinetics of the analytical reaction. Results: Briefly, our toolkit ensures an exact membrane alignment, utilizing basic computer vision techniques. It also provides a stable method to estimate the background light level. Finally, we model the light production over time, utilizing the knowledge about the reaction kinetics of the underlying horseradish peroxidase-based signal detection method. Conclusion: proMAD incorporates the reaction kinetics of the enzyme to model the signal development over time for each membrane creating an individual, self-referencing concept. Variations of membranes within a given experimental set up can be accounted for, allowing for a better comparison of such. While the open-source library can be implemented in existing workflows and used for highly user-Tailored analytic setups, the web application, on the other hand, provides easy platform-independent access to the core algorithm to a wide range of researchers. proMAD's inherent flexibility has the potential to cover a wide range of use-cases and enables the automation of data analytic tasks. © 2020 The Author(s).},
      author_keywords={Densitometry; Membrane antibody array; Protein microarray; Python; Web application},
      keywords={Antibodies; Association reactions; Biochips; Chemical detection; Data handling; Image enhancement; Kinetics; Open source software; Reaction kinetics; Reliability analysis; Software reliability, Antibody arrays; Densitometry; Protein microarray; Python; WEB application, Membranes, algorithm; densitometry; enzyme immunoassay; procedures; protein microarray; software; workflow, Algorithms; Densitometry; Immunoenzyme Techniques; Protein Array Analysis; Software; Workflow},
      correspondence_address1={Eckert, H.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: hagen.eckert@tu-dresden.de},
      publisher={BioMed Central Ltd.},
      issn={14712105},
      coden={BBMIC},
      pubmed_id={32093608},
      language={English},
      abbrev_source_title={BMC Bioinform.},
      document_type={Article},
      source={Scopus},
      }

  • Mechanical Transmission of Rotational Motion between Molecular-Scale Gears
    • H. -H. Lin, A. Croy, R. Gutierrez, C. Joachim, G. Cuniberti
    • Physical Review Applied 13, 034024 (2020)
    • DOI   Abstract  

      The manipulation and coupling of molecule gears is the first step toward realizing molecular-scale mechanical machines. Here, we theoretically investigate the behavior of such gears using molecular-dynamics simulations. Within a nearly rigid-body approximation, we reduce the dynamics of the gears to the rotational motion around the orientation vector. This allows us to study their behavior based on a few collective variables. Specifically, for a single hexa(4-tert-butylphenyl)benzene molecule, we show that the rotational-angle dynamics correspond to those of a Brownian rotor. For two such coupled gears, we extract the effective interaction potential and find that it is strongly dependent on the center-of-mass distance. Finally, we study the collective motion of a train of gears. We demonstrate the existence of three different regimes, depending on the magnitude of the driving torque of the first gear: Underdriving, driving, and overdriving, which correspond, respectively, to no collective rotation, collective rotation, and only single-gear rotation. This behavior can be understood in terms of a simplified interaction potential. © 2020 American Physical Society.

      @ARTICLE{Lin2020,
      author={Lin, H.-H. and Croy, A. and Gutierrez, R. and Joachim, C. and Cuniberti, G.},
      title={Mechanical Transmission of Rotational Motion between Molecular-Scale Gears},
      journal={Physical Review Applied},
      year={2020},
      volume={13},
      number={3},
      doi={10.1103/PhysRevApplied.13.034024},
      art_number={034024},
      note={cited By 7},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85082880360&doi=10.1103%2fPhysRevApplied.13.034024&partnerID=40&md5=ec1c9ba5f0f4d073855055e44f15151e},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, Tu Dresden, Dresden, 01069, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany; Gns and Mana Satellite, CEMES-CNRS, 29 rue J. Marvig, Toulouse Cedex, 31055, France; Dresden Center for Computational Materials Science, Tu Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, Tu Dresden, 01062 Dresden, Germany, Germany},
      abstract={The manipulation and coupling of molecule gears is the first step toward realizing molecular-scale mechanical machines. Here, we theoretically investigate the behavior of such gears using molecular-dynamics simulations. Within a nearly rigid-body approximation, we reduce the dynamics of the gears to the rotational motion around the orientation vector. This allows us to study their behavior based on a few collective variables. Specifically, for a single hexa(4-tert-butylphenyl)benzene molecule, we show that the rotational-angle dynamics correspond to those of a Brownian rotor. For two such coupled gears, we extract the effective interaction potential and find that it is strongly dependent on the center-of-mass distance. Finally, we study the collective motion of a train of gears. We demonstrate the existence of three different regimes, depending on the magnitude of the driving torque of the first gear: Underdriving, driving, and overdriving, which correspond, respectively, to no collective rotation, collective rotation, and only single-gear rotation. This behavior can be understood in terms of a simplified interaction potential. © 2020 American Physical Society.},
      keywords={Molecular dynamics; Molecules; Rotational flow; Transmissions, Collective motions; Collective variables; Effective interactions; Interaction potentials; Mechanical machines; Mechanical transmission; Molecular dynamics simulations; Rigid body approximations, Rotation},
      publisher={American Physical Society},
      issn={23317019},
      language={English},
      abbrev_source_title={Phys. Rev. Appl.},
      document_type={Article},
      source={Scopus},
      }

  • Nanosensors-Assisted quantitative analysis of biochemical processes in droplets
    • D. Belyaev, J. Schütt, B. Ibarlucea, T. Rim, L. Baraban, G. Cuniberti
    • Micromachines 11, 138 (2020)
    • DOI   Abstract  

      Here, we present a miniaturized lab-on-a-chip detecting system for an all-electric and label-free analysis of the emulsion droplets incorporating the nanoscopic silicon nanowires-based field-effect transistors (FETs). We specifically focus on the analysis of β-galactosidase e.g., activity, which is an important enzyme of the glycolysis metabolic pathway. Furthermore, the efficiency of the synthesis and action of β-galactosidase can be one of the markers for several diseases, e.g., cancer, hyper/hypoglycemia, cell senescence, or other disruptions in cell functioning. We measure the reaction and reaction kinetics-associated shift of the source-to-drain current Isd in the system, which is caused by the change of the ionic strength of the microenvironment. With these results, we demonstrate that the ion-sensitive FETs are able to sense the interior of the aqueous reactors; thus, the conjunction of miniature nanosensors and droplet-based microfluidic systems conceptually opens a new route toward a sensitive, optics-less analysis of biochemical processes. © 2020 by the authors.

      @ARTICLE{Belyaev2020,
      author={Belyaev, D. and Schütt, J. and Ibarlucea, B. and Rim, T. and Baraban, L. and Cuniberti, G.},
      title={Nanosensors-Assisted quantitative analysis of biochemical processes in droplets},
      journal={Micromachines},
      year={2020},
      volume={11},
      number={2},
      doi={10.3390/mi11020138},
      art_number={138},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081283806&doi=10.3390%2fmi11020138&partnerID=40&md5=e1150f9256f6ee93f4b910054e17906b},
      affiliation={Max Bergmann Center of Biomaterials and Institute for Materials Science, Technische Universität Dresden, Dresden, 01069, Germany; Technische Universität Dresden, Center for Advancing Electronics Dresden, Dresden, 01062, Germany; Department of Creative IT Engineering, Pohang University of Science and Technology, Pohang, 37673, South Korea; Dresden Center for Computational Materials Science, Dresden, 01062, Germany},
      abstract={Here, we present a miniaturized lab-on-a-chip detecting system for an all-electric and label-free analysis of the emulsion droplets incorporating the nanoscopic silicon nanowires-based field-effect transistors (FETs). We specifically focus on the analysis of β-galactosidase e.g., activity, which is an important enzyme of the glycolysis metabolic pathway. Furthermore, the efficiency of the synthesis and action of β-galactosidase can be one of the markers for several diseases, e.g., cancer, hyper/hypoglycemia, cell senescence, or other disruptions in cell functioning. We measure the reaction and reaction kinetics-associated shift of the source-to-drain current Isd in the system, which is caused by the change of the ionic strength of the microenvironment. With these results, we demonstrate that the ion-sensitive FETs are able to sense the interior of the aqueous reactors; thus, the conjunction of miniature nanosensors and droplet-based microfluidic systems conceptually opens a new route toward a sensitive, optics-less analysis of biochemical processes. © 2020 by the authors.},
      author_keywords={Droplet-based microfluidics; Enzymatic reaction; Lab-on-a-chip; Nanosensor; Point-of-care diagnostics; Silicon nanowire-based field-effect transistor; ß-galactosidase assay},
      keywords={Diagnosis; Drain current; Drops; Electric field effects; Emulsification; Emulsions; Ionic strength; Lab-on-a-chip; Microfluidics; Nanosensors; Nanowires; Reaction kinetics, Droplet-based microfluidics; Enzymatic reaction; Galactosidases; Point of care diagnostic; Silicon nanowires, Field effect transistors},
      correspondence_address1={Belyaev, D.; Max Bergmann Center of Biomaterials and Institute for Materials Science, Germany; email: dmitry.belyaev@nano.tu-dresden.de},
      publisher={MDPI AG},
      issn={2072666X},
      language={English},
      abbrev_source_title={Micromachines},
      document_type={Article},
      source={Scopus},
      }

  • Enhanced photocatalytic activity of au/TiO2 nanoparticles against ciprofloxacin
    • P. Martins, S. Kappert, H. N. Le, V. Sebastian, K. Kühn, M. Alves, L. Pereira, G. Cuniberti, M. Melle-Franco, S. Lanceros-Méndez
    • Catalysts 10, 234 (2020)
    • DOI   Abstract  

      In the last decades, photocatalysis has arisen as a solution to degrade emerging pollutants such as antibiotics. However, the reduced photoactivation of TiO2 under visible radiation constitutes a major drawback because 95% of sunlight radiation is not being used in this process. Thus, it is critical to modify TiO2 nanoparticles to improve the ability to absorb visible radiation from sunlight. This work reports on the synthesis of TiO2 nanoparticles decorated with gold (Au) nanoparticles by deposition-precipitation method for enhanced photocatalytic activity. The produced nanocomposites absorb 40% to 55% more radiation in the visible range than pristine TiO2, the best results being obtained for the synthesis performed at 25◦C and with Au loading of 0.05 to 0.1 wt. %. Experimental tests yielded a higher photocatalytic degradation of 91% and 49% of ciprofloxacin (5 mg/L) under UV and visible radiation, correspondingly. Computational modeling supports the experimental results, showing the ability of Au to bind TiO2 anatase surfaces, the relevant role of Au transferring electrons, and the high affinity of ciprofloxacin to both Au and TiO2 surfaces. Hence, the present work represents a reliable approach to produce efficient photocatalytic materials and an overall contribution in the development of high-performance Au/TiO2 photocatalytic nanostructures through the optimization of the synthesis parameters, photocatalytic conditions, and computational modeling. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

      @ARTICLE{Martins2020,
      author={Martins, P. and Kappert, S. and Le, H.N. and Sebastian, V. and Kühn, K. and Alves, M. and Pereira, L. and Cuniberti, G. and Melle-Franco, M. and Lanceros-Méndez, S.},
      title={Enhanced photocatalytic activity of au/TiO2 nanoparticles against ciprofloxacin},
      journal={Catalysts},
      year={2020},
      volume={10},
      number={2},
      doi={10.3390/catal10020234},
      art_number={234},
      note={cited By 19},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079661606&doi=10.3390%2fcatal10020234&partnerID=40&md5=8149b222aa2ccd735e37d80e7175f797},
      affiliation={Department of Physics/Centre of Biological Engineering, University of Minho, Braga, 4710-057, Portugal; IB-S—Institute for Research and Innovation on Bio-Sustainability, University of Minho, Braga, 4710-057, Portugal; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden Dresden, Dresden, 01062, Germany; Department of Chemical Engineering, Hanoi University of Science and Technology, Hanoi, 10000, Viet Nam; Department of Chemical Engineering, Aragon Institute of Nanoscience (INA), University of Zaragoza, Campus Río Ebro-Edificio I+D, C/Poeta Mariano Esquillor S/N, Zaragoza, 50018, Spain; Networking Research Centre on Bioengineering, Biomaterials and Nanomedicine, Centro de Investigacion Biomédica en Red—Bioengenharía, Biomateriales e Nanomedicina, Madrid, 28029, Spain; Dresden Center for Computational Materials Science, Technische Universität Dresden Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden Dresden, Dresden, 01062, Germany; Centro de Investigação em Materiais Cerâmicos e Compósitos, Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, Aveiro, 3810-193, Portugal; BCMaterials, Basque Center for Materials, Applications, and Nanostructures, Universidad del País Basco—Euskal Herriko Unibertsitatea, Science Park, Leioa, 48940, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain},
      abstract={In the last decades, photocatalysis has arisen as a solution to degrade emerging pollutants such as antibiotics. However, the reduced photoactivation of TiO2 under visible radiation constitutes a major drawback because 95% of sunlight radiation is not being used in this process. Thus, it is critical to modify TiO2 nanoparticles to improve the ability to absorb visible radiation from sunlight. This work reports on the synthesis of TiO2 nanoparticles decorated with gold (Au) nanoparticles by deposition-precipitation method for enhanced photocatalytic activity. The produced nanocomposites absorb 40% to 55% more radiation in the visible range than pristine TiO2, the best results being obtained for the synthesis performed at 25◦C and with Au loading of 0.05 to 0.1 wt. %. Experimental tests yielded a higher photocatalytic degradation of 91% and 49% of ciprofloxacin (5 mg/L) under UV and visible radiation, correspondingly. Computational modeling supports the experimental results, showing the ability of Au to bind TiO2 anatase surfaces, the relevant role of Au transferring electrons, and the high affinity of ciprofloxacin to both Au and TiO2 surfaces. Hence, the present work represents a reliable approach to produce efficient photocatalytic materials and an overall contribution in the development of high-performance Au/TiO2 photocatalytic nanostructures through the optimization of the synthesis parameters, photocatalytic conditions, and computational modeling. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.},
      author_keywords={Antibiotics; Au-TiO2; Emergent contaminants; GFN-xTB; Nanocatalyst; Photocatalysis},
      correspondence_address1={Martins, P.; Department of Physics/Centre of Biological Engineering, Portugal; email: pamartins@fisica.uminho.pt},
      publisher={MDPI},
      issn={20734344},
      language={English},
      abbrev_source_title={Catalysts},
      document_type={Article},
      source={Scopus},
      }

  • An efficient phase-field model for fatigue fracture in ductile materials
    • M. Seiler, T. Linse, P. Hantschke, M. Kästner
    • Engineering Fracture Mechanics 224, 106807 (2020)
    • DOI   Abstract  

      Fatigue fracture in ductile materials, e.g. metals, is caused by cyclic plasticity. Especially regarding the high numbers of load cycles, plastic material models resolving the full loading path are computationally very demanding. Herein, a model with particularly small computational effort is presented. It provides a macroscopic, phenomenological description of fatigue fracture by combining the phase-field method for brittle fracture with a classic durability concept. A local lifetime variable is obtained, which degrades the fracture resistance progressively. By deriving the stress-strain path from cyclic material characteristics, only one increment per load cycle is needed at maximum. The model allows to describe fatigue crack initiation, propagation and residual fracture and can reproduce Paris behaviour. © 2019 Elsevier Ltd

      @ARTICLE{Seiler2020,
      author={Seiler, M. and Linse, T. and Hantschke, P. and Kästner, M.},
      title={An efficient phase-field model for fatigue fracture in ductile materials},
      journal={Engineering Fracture Mechanics},
      year={2020},
      volume={224},
      doi={10.1016/j.engfracmech.2019.106807},
      art_number={106807},
      note={cited By 33},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076558659&doi=10.1016%2fj.engfracmech.2019.106807&partnerID=40&md5=f0ce2ee119e880df456c5fa7eccf527b},
      affiliation={Chair of Computational and Experimental Solid Mechanics, TU Dresden, Dresden, Germany; Structural Durability Group, TU Dresden, Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, Germany},
      abstract={Fatigue fracture in ductile materials, e.g. metals, is caused by cyclic plasticity. Especially regarding the high numbers of load cycles, plastic material models resolving the full loading path are computationally very demanding. Herein, a model with particularly small computational effort is presented. It provides a macroscopic, phenomenological description of fatigue fracture by combining the phase-field method for brittle fracture with a classic durability concept. A local lifetime variable is obtained, which degrades the fracture resistance progressively. By deriving the stress-strain path from cyclic material characteristics, only one increment per load cycle is needed at maximum. The model allows to describe fatigue crack initiation, propagation and residual fracture and can reproduce Paris behaviour. © 2019 Elsevier Ltd},
      author_keywords={Ductile; Fatigue; Local strain approach; Paris law; Phase-field},
      keywords={Ductility; Fracture; Phase transitions, Computational effort; Ductile; Fatigue crack initiation; Local-strain approach; Material characteristics; Paris law; Phase fields; Phenomenological description, Fatigue of materials},
      correspondence_address1={Kästner, M.; Chair of Computational and Experimental Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={00137944},
      coden={EFMEA},
      language={English},
      abbrev_source_title={Eng. Fract. Mech.},
      document_type={Article},
      source={Scopus},
      }

  • Dirac fermions and flat bands in the ideal kagome metal FeSn
    • M. Kang, L. Ye, S. Fang, J. -S. You, A. Levitan, M. Han, J. I. Facio, C. Jozwiak, A. Bostwick, E. Rotenberg, M. K. Chan, R. D. McDonald, D. Graf, K. Kaznatcheev, E. Vescovo, D. C. Bell, E. Kaxiras, J. van den Brink, M. Richter, M. Prasad Ghimire, J. G. Checkelsky, R. Comin
    • Nature Materials 19, 163-169 (2020)
    • DOI   Abstract  

      A kagome lattice of 3d transition metal ions is a versatile platform for correlated topological phases hosting symmetry-protected electronic excitations and magnetic ground states. However, the paradigmatic states of the idealized two-dimensional kagome lattice—Dirac fermions and flat bands—have not been simultaneously observed. Here, we use angle-resolved photoemission spectroscopy and de Haas–van Alphen quantum oscillations to reveal coexisting surface and bulk Dirac fermions as well as flat bands in the antiferromagnetic kagome metal FeSn, which has spatially decoupled kagome planes. Our band structure calculations and matrix element simulations demonstrate that the bulk Dirac bands arise from in-plane localized Fe-3d orbitals, and evidence that the coexisting Dirac surface state realizes a rare example of fully spin-polarized two-dimensional Dirac fermions due to spin-layer locking in FeSn. The prospect to harness these prototypical excitations in a kagome lattice is a frontier of great promise at the confluence of topology, magnetism and strongly correlated physics. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.

      @ARTICLE{Kang2020163,
      author={Kang, M. and Ye, L. and Fang, S. and You, J.-S. and Levitan, A. and Han, M. and Facio, J.I. and Jozwiak, C. and Bostwick, A. and Rotenberg, E. and Chan, M.K. and McDonald, R.D. and Graf, D. and Kaznatcheev, K. and Vescovo, E. and Bell, D.C. and Kaxiras, E. and van den Brink, J. and Richter, M. and Prasad Ghimire, M. and Checkelsky, J.G. and Comin, R.},
      title={Dirac fermions and flat bands in the ideal kagome metal FeSn},
      journal={Nature Materials},
      year={2020},
      volume={19},
      number={2},
      pages={163-169},
      doi={10.1038/s41563-019-0531-0},
      note={cited By 188},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076512559&doi=10.1038%2fs41563-019-0531-0&partnerID=40&md5=ec66db33a2ea68a44b84f7d39091e452},
      affiliation={Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, United States; Department of Physics, Harvard University, Cambridge, MA, United States; Leibniz Institute for Solid State and Materials Research, IFW Dresden, Dresden, Germany; Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA, United States; National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, NM, United States; National High Magnetic Field Laboratory, Tallahassee, FL, United States; National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, United States; John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States; Center for Nanoscale systems, Harvard University, Cambridge, MA, United States; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, Germany; Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, Nepal},
      abstract={A kagome lattice of 3d transition metal ions is a versatile platform for correlated topological phases hosting symmetry-protected electronic excitations and magnetic ground states. However, the paradigmatic states of the idealized two-dimensional kagome lattice—Dirac fermions and flat bands—have not been simultaneously observed. Here, we use angle-resolved photoemission spectroscopy and de Haas–van Alphen quantum oscillations to reveal coexisting surface and bulk Dirac fermions as well as flat bands in the antiferromagnetic kagome metal FeSn, which has spatially decoupled kagome planes. Our band structure calculations and matrix element simulations demonstrate that the bulk Dirac bands arise from in-plane localized Fe-3d orbitals, and evidence that the coexisting Dirac surface state realizes a rare example of fully spin-polarized two-dimensional Dirac fermions due to spin-layer locking in FeSn. The prospect to harness these prototypical excitations in a kagome lattice is a frontier of great promise at the confluence of topology, magnetism and strongly correlated physics. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.},
      keywords={Binary alloys; Ground state; Locks (fasteners); Metal ions; Photoelectron spectroscopy; Tin alloys; Topology; Transition metal compounds; Transition metals, 3d transition metals; Angle resolved photoemission spectroscopy; Antiferromagnetics; Band structure calculation; Electronic excitation; Fully spin-polarized; Magnetic ground state; Quantum oscillations, Iron alloys},
      correspondence_address1={Checkelsky, J.G.; Department of Physics, United States; email: checkelsky@mit.edu},
      publisher={Nature Research},
      issn={14761122},
      coden={NMAAC},
      pubmed_id={31819211},
      language={English},
      abbrev_source_title={Nat. Mater.},
      document_type={Article},
      source={Scopus},
      }

  • Dodecacene Generated on Surface: Reopening of the Energy Gap
    • F. Eisenhut, T. Kühne, F. García, S. Fernández, E. Guitián, D. Pérez, G. Trinquier, G. Cuniberti, C. Joachim, D. Peña, F. Moresco
    • ACS Nano 14, 1011-1017 (2020)
    • DOI   Abstract  

      The acene series represents a model system to investigate the intriguing electronic properties of extended π-electron structures in the one-dimensional limit, which are important for applications in electronics and spintronics and for the fundamental understanding of electronic transport. Here, we present the on-surface generation of the longest acene obtained so far: dodecacene. Scanning tunneling spectroscopy gives access to the energy position and spatial distribution of its electronic states on the Au(111) surface. We observe that, after a progressive closing of the gap and a stabilization to about 1 eV at the length of decacene and undecacene, the energy gap of dodecacene unexpectedly increases to 1.4 eV. Considering the acene series as an exemplary general case, we discuss the evolution with length of the single tunneling resonances in comparison with ionization energy, electronic affinity, and optical gap. Copyright © 2019 American Chemical Society.

      @ARTICLE{Eisenhut20201011,
      author={Eisenhut, F. and Kühne, T. and García, F. and Fernández, S. and Guitián, E. and Pérez, D. and Trinquier, G. and Cuniberti, G. and Joachim, C. and Peña, D. and Moresco, F.},
      title={Dodecacene Generated on Surface: Reopening of the Energy Gap},
      journal={ACS Nano},
      year={2020},
      volume={14},
      number={1},
      pages={1011-1017},
      doi={10.1021/acsnano.9b08456},
      note={cited By 51},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077014331&doi=10.1021%2facsnano.9b08456&partnerID=40&md5=4db539b2ca3b61ab0a68e2a4df9a372d},
      affiliation={Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01069, Germany; Institute for Materials Science, TU Dresden, Dresden, 01069, Germany; Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01069, Germany; GNS and MANA Satellite, CEMES, CNRS, 29 rue J. Marvig, Cedex Toulouse, 31055, France; Laboratoire de Chimie et Physique Quantiques, IRSAMC-CNRS-UMR5626, Université Paul-Sabatier (Toulouse III), Cedex 4 Toulouse, 31062, France},
      abstract={The acene series represents a model system to investigate the intriguing electronic properties of extended π-electron structures in the one-dimensional limit, which are important for applications in electronics and spintronics and for the fundamental understanding of electronic transport. Here, we present the on-surface generation of the longest acene obtained so far: dodecacene. Scanning tunneling spectroscopy gives access to the energy position and spatial distribution of its electronic states on the Au(111) surface. We observe that, after a progressive closing of the gap and a stabilization to about 1 eV at the length of decacene and undecacene, the energy gap of dodecacene unexpectedly increases to 1.4 eV. Considering the acene series as an exemplary general case, we discuss the evolution with length of the single tunneling resonances in comparison with ionization energy, electronic affinity, and optical gap. Copyright © 2019 American Chemical Society.},
      author_keywords={dodecacene; electronic resonances; energy gap; on-surface synthesis; poly-radical character; scanning tunneling microscopy; scanning tunneling spectroscopy},
      keywords={Electronic properties; Scanning tunneling microscopy; Spectroscopy, dodecacene; Electron structures; Electronic resonance; Electronic transport; poly-radical character; Scanning tunneling spectroscopy; Surface generations; Tunneling resonances, Energy gap},
      correspondence_address1={Peña, D.; Centro de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Spain; email: diego.pena@usc.es},
      publisher={American Chemical Society},
      issn={19360851},
      pubmed_id={31829618},
      language={English},
      abbrev_source_title={ACS Nano},
      document_type={Article},
      source={Scopus},
      }

  • GITT Analysis of Lithium Insertion Cathodes for Determining the Lithium Diffusion Coefficient at Low Temperature: Challenges and Pitfalls
    • A. Nickol, T. Schied, C. Heubner, M. Schneider, A. Michaelis, M. Bobeth, G. Cuniberti
    • Journal of the Electrochemical Society 167, 090546 (2020)
    • DOI   Abstract  

      Understanding the diffusion of lithium ions in electrode materials for lithium ion batteries is of great importance for their knowledge-based optimization and development of novel materials and cell designs. The galvanostatic intermittent titration technique (GITT) is widely applied in battery research to study the diffusion of lithium in anode and cathode materials depending on the degree of lithiation. While transport properties of electrode materials at high and ambient temperatures are largely available, low temperature diffusion and rate coefficients are hardly reported in the literature and vary by orders of magnitude for identical active materials. Herein, we demonstrate and discuss several challenges and pitfalls in the application and evaluation of GITT measurements for determining the effective chemical lithium ion diffusion coefficient in lithium insertion electrodes, which become especially important at low temperature. This includes theoretical considerations and an experimental analysis of the promising cathode material LiNi0.5Co0.2Mn0.3O2 (NCM523) in the wide temperature range of -40 °C to 40 °C. We show how the choice of experimental conditions for the GITT measurements and of the subsequent mathematical evaluation significantly influence the derived diffusion coefficient. The results suggest that the large scattering of reported values of the diffusion coefficient could be caused by the use of different evaluation procedures. Simple calculation methods appear to be less suited the lower the temperature is. It is shown that the complementary use of GITT and EIS supplemented by detailed knowledge of the microstructure of the electrode significantly improves the accuracy of determining the diffusion coefficient. © 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.

      @ARTICLE{Nickol2020,
      author={Nickol, A. and Schied, T. and Heubner, C. and Schneider, M. and Michaelis, A. and Bobeth, M. and Cuniberti, G.},
      title={GITT Analysis of Lithium Insertion Cathodes for Determining the Lithium Diffusion Coefficient at Low Temperature: Challenges and Pitfalls},
      journal={Journal of the Electrochemical Society},
      year={2020},
      volume={167},
      number={9},
      doi={10.1149/1945-7111/ab9404},
      art_number={090546},
      note={cited By 64},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85086026731&doi=10.1149%2f1945-7111%2fab9404&partnerID=40&md5=d6716f8c553725a34d99d48c8f6e9b95},
      affiliation={Fraunhofer IKTS, Fraunhofer Institute for Ceramic Technologies and Systems Dresden, Dresden, 01277, Germany; Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Understanding the diffusion of lithium ions in electrode materials for lithium ion batteries is of great importance for their knowledge-based optimization and development of novel materials and cell designs. The galvanostatic intermittent titration technique (GITT) is widely applied in battery research to study the diffusion of lithium in anode and cathode materials depending on the degree of lithiation. While transport properties of electrode materials at high and ambient temperatures are largely available, low temperature diffusion and rate coefficients are hardly reported in the literature and vary by orders of magnitude for identical active materials. Herein, we demonstrate and discuss several challenges and pitfalls in the application and evaluation of GITT measurements for determining the effective chemical lithium ion diffusion coefficient in lithium insertion electrodes, which become especially important at low temperature. This includes theoretical considerations and an experimental analysis of the promising cathode material LiNi0.5Co0.2Mn0.3O2 (NCM523) in the wide temperature range of -40 °C to 40 °C. We show how the choice of experimental conditions for the GITT measurements and of the subsequent mathematical evaluation significantly influence the derived diffusion coefficient. The results suggest that the large scattering of reported values of the diffusion coefficient could be caused by the use of different evaluation procedures. Simple calculation methods appear to be less suited the lower the temperature is. It is shown that the complementary use of GITT and EIS supplemented by detailed knowledge of the microstructure of the electrode significantly improves the accuracy of determining the diffusion coefficient. © 2020 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.},
      keywords={Anodes; Cathode materials; Cathodes; Cobalt compounds; Ions; Knowledge based systems; Lithium compounds; Lithium-ion batteries; Manganese compounds; Nickel compounds; Nitrogen compounds; Temperature, Experimental analysis; Experimental conditions; Galvanostatic Intermittent Titration Techniques; Lithium insertion electrodes; Lithium ion diffusion; Low-temperature diffusion; Simple calculation method; Wide temperature ranges, Diffusion},
      publisher={Institute of Physics Publishing},
      issn={00134651},
      coden={JESOA},
      language={English},
      abbrev_source_title={J Electrochem Soc},
      document_type={Article},
      source={Scopus},
      }

  • Spin-polarized electron transmission in dna-like systems
    • M. A. Sierra, D. Sánchez, R. Gutierrez, G. Cuniberti, F. Domínguez-Adame, E. Díaz
    • Biomolecules 10, 49 (2020)
    • DOI   Abstract  

      The helical distribution of the electronic density in chiral molecules, such as DNA and bacteriorhodopsin, has been suggested to induce a spin–orbit coupling interaction that may lead to the so-called chirality-induced spin selectivity (CISS) effect. Key ingredients for the theoretical modelling are, in this context, the helically shaped potential of the molecule and, concomitantly, a Rashba-like spin–orbit coupling due to the appearance of a magnetic field in the electron reference frame. Symmetries of these models clearly play a crucial role in explaining the observed effect, but a thorough analysis has been largely ignored in the literature. In this work, we present a study of these symmetries and how they can be exploited to enhance chiral-induced spin selectivity in helical molecular systems. c○ 2019 by the authors. Licensee MDPI, Basel, Switzerland.

      @ARTICLE{Sierra2020,
      author={Sierra, M.A. and Sánchez, D. and Gutierrez, R. and Cuniberti, G. and Domínguez-Adame, F. and Díaz, E.},
      title={Spin-polarized electron transmission in dna-like systems},
      journal={Biomolecules},
      year={2020},
      volume={10},
      number={1},
      doi={10.3390/biom10010049},
      art_number={49},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85077494423&doi=10.3390%2fbiom10010049&partnerID=40&md5=8c0a862ccfc59c3812d0453ebd176ad6},
      affiliation={Institute for Cross-Disciplinary Physics and Complex Systems IFISC (UIB-CSIC), Palma de Mallorca, E-07122, Spain; Institut für Theoretische Physik (TP4) and Würzburg, Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Würzburg, 97074, Germany; Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; GISC, Departamento de Física de Materiales, Universidad Complutense, Madrid, E-28040, Spain},
      abstract={The helical distribution of the electronic density in chiral molecules, such as DNA and bacteriorhodopsin, has been suggested to induce a spin–orbit coupling interaction that may lead to the so-called chirality-induced spin selectivity (CISS) effect. Key ingredients for the theoretical modelling are, in this context, the helically shaped potential of the molecule and, concomitantly, a Rashba-like spin–orbit coupling due to the appearance of a magnetic field in the electron reference frame. Symmetries of these models clearly play a crucial role in explaining the observed effect, but a thorough analysis has been largely ignored in the literature. In this work, we present a study of these symmetries and how they can be exploited to enhance chiral-induced spin selectivity in helical molecular systems. c○ 2019 by the authors. Licensee MDPI, Basel, Switzerland.},
      author_keywords={Chirality-induced spin selectivity; DNA electronic transport; Helical molecules; Spin polarization; Spin transport},
      keywords={article; chirality; polarization; chemical model; chemistry; electron; quantum theory, bacteriorhodopsin; DNA, Bacteriorhodopsins; DNA; Electrons; Models, Chemical; Quantum Theory},
      correspondence_address1={Domínguez-Adame, F.; GISC, Spain; email: adame@ucm.es},
      publisher={MDPI AG},
      issn={2218273X},
      pubmed_id={31905610},
      language={English},
      abbrev_source_title={Biomolecules},
      document_type={Article},
      source={Scopus},
      }

2019

  • Topological Electronic Structure and Intrinsic Magnetization in MnBi4Te7: A Bi2Te3 Derivative with a Periodic Mn Sublattice
    • R. C. Vidal, A. Zeugner, J. I. Facio, R. Ray, M. H. Haghighi, A. U. B. Wolter, L. T. Corredor Bohorquez, F. Caglieris, S. Moser, T. Figgemeier, T. R. F. Peixoto, H. B. Vasili, M. Valvidares, S. Jung, C. Cacho, A. Alfonsov, K. Mehlawat, V. Kataev, C. Hess, M. Richter, B. Büchner, J. Van Den Brink, M. Ruck, F. Reinert, H. Bentmann, A. Isaeva
    • Physical Review X 91, 041065 (2019)
    • DOI   Abstract  

      Combinations of nontrivial band topology and long-range magnetic order hold promise for realizations of novel spintronic phenomena, such as the quantum anomalous Hall effect and the topological magnetoelectric effect. Following theoretical advances, material candidates are emerging. Yet, so far a compound that combines a band-inverted electronic structure with an intrinsic net magnetization remains unrealized. MnBi2Te4 has been established as the first antiferromagnetic topological insulator and constitutes the progenitor of a modular (Bi2Te3)n(MnBi2Te4) series. Here, for n=1, we confirm a nonstoichiometric composition proximate to MnBi4Te7. We establish an antiferromagnetic state below 13 K followed by a state with a net magnetization and ferromagnetic-like hysteresis below 5 K. Angle-resolved photoemission experiments and density-functional calculations reveal a topologically nontrivial surface state on the MnBi4Te7(0001) surface, analogous to the nonmagnetic parent compound Bi2Te3. Our results establish MnBi4Te7 as the first band-inverted compound with intrinsic net magnetization providing a versatile platform for the realization of magnetic topological states of matter. © 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the “https://creativecommons.org/licenses/by/4.0/” Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

      @ARTICLE{Vidal2019,
      author={Vidal, R.C. and Zeugner, A. and Facio, J.I. and Ray, R. and Haghighi, M.H. and Wolter, A.U.B. and Corredor Bohorquez, L.T. and Caglieris, F. and Moser, S. and Figgemeier, T. and Peixoto, T.R.F. and Vasili, H.B. and Valvidares, M. and Jung, S. and Cacho, C. and Alfonsov, A. and Mehlawat, K. and Kataev, V. and Hess, C. and Richter, M. and Büchner, B. and Van Den Brink, J. and Ruck, M. and Reinert, F. and Bentmann, H. and Isaeva, A.},
      title={Topological Electronic Structure and Intrinsic Magnetization in MnBi4Te7: A Bi2Te3 Derivative with a Periodic Mn Sublattice},
      journal={Physical Review X},
      year={2019},
      volume={91},
      number={4},
      doi={10.1103/PhysRevX.9.041065},
      art_number={041065},
      note={cited By 81},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078344525&doi=10.1103%2fPhysRevX.9.041065&partnerID=40&md5=12ef5fe541d57037e8aead8afaa91ed0},
      affiliation={Experimental Physics VII, Universität Würzburg, Würzburg, D-97074, Germany; Würzburg-Dresden Cluster of Excellence Ct.qmat, Germany; Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Dresden, D-01062, Germany; Leibniz IFW Dresden, Helmholtzstraße 20, Dresden, D-01069, Germany; Experimental Physics IV, Universität Würzburg, Würzburg, D-97074, Germany; Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States; ALBA Synchrotron Light Source, Cerdanyola del Valles, E-08290, Spain; Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, D-01062, Germany; Faculty of Physics, Technische Universität Dresden, Dresden, D-01062, Germany; Max Planck Institute for Chemical Physics of Solids, Dresden, D-01187, Germany},
      abstract={Combinations of nontrivial band topology and long-range magnetic order hold promise for realizations of novel spintronic phenomena, such as the quantum anomalous Hall effect and the topological magnetoelectric effect. Following theoretical advances, material candidates are emerging. Yet, so far a compound that combines a band-inverted electronic structure with an intrinsic net magnetization remains unrealized. MnBi2Te4 has been established as the first antiferromagnetic topological insulator and constitutes the progenitor of a modular (Bi2Te3)n(MnBi2Te4) series. Here, for n=1, we confirm a nonstoichiometric composition proximate to MnBi4Te7. We establish an antiferromagnetic state below 13 K followed by a state with a net magnetization and ferromagnetic-like hysteresis below 5 K. Angle-resolved photoemission experiments and density-functional calculations reveal a topologically nontrivial surface state on the MnBi4Te7(0001) surface, analogous to the nonmagnetic parent compound Bi2Te3. Our results establish MnBi4Te7 as the first band-inverted compound with intrinsic net magnetization providing a versatile platform for the realization of magnetic topological states of matter. © 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/" Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.},
      keywords={Antiferromagnetism; Electronic structure; Magnetization; Manganese; Quantum Hall effect; Tellurium compounds; Topological insulators; Topology, Angle-resolved photoemission; Anomalous hall effects; Antiferromagnetic state; Antiferromagnetics; Long range magnetic order; Material candidate; Non-stoichiometric composition; Topological state, Bismuth compounds},
      publisher={American Physical Society},
      issn={21603308},
      language={English},
      abbrev_source_title={Phys. Rev. X},
      document_type={Article},
      source={Scopus},
      }

  • Creating Weyl nodes and controlling their energy by magnetization rotation
    • M. P. Ghimire, J. I. Facio, J. -S. You, L. Ye, J. G. Checkelsky, S. Fang, E. Kaxiras, M. Richter, J. Van Den Brink
    • Physical Review Research 1, 032044 (2019)
    • DOI   Abstract  

      As they do not rely on the presence of any crystal symmetry, Weyl nodes are robust topological features of an electronic structure that can occur at any momentum and energy. Acting as sinks and sources of Berry curvature, Weyl nodes have been predicted to strongly affect the transverse electronic response, like in the anomalous Hall or Nernst effects. However, to observe large anomalous effects the Weyl nodes need to be close to or at the Fermi level, which implies the band structure must be tuned by an external parameter, e.g., chemical doping. Here we show that in a ferromagnetic metal tuning of the Weyl node energy and momentum can be achieved by rotation of the magnetization. First, taking as example the elementary magnet hcp-Co, we use electronic structure calculations based on density-functional theory to show that by canting the magnetization away from the easy axis, Weyl nodes can be driven exactly to the Fermi surface. Second, we show that the same phenomenology applies to the kagome ferromagnet Co3Sn2S2, in which we additionally show how the dynamics in energy and momentum of the Weyl nodes affects the calculated anomalous Hall and Nernst conductivities. Our results highlight how the intrinsic magnetic anisotropy can be used to engineer Weyl physics. © 2019 authors. Published by the American Physical Society.

      @ARTICLE{Ghimire2019,
      author={Ghimire, M.P. and Facio, J.I. and You, J.-S. and Ye, L. and Checkelsky, J.G. and Fang, S. and Kaxiras, E. and Richter, M. and Van Den Brink, J.},
      title={Creating Weyl nodes and controlling their energy by magnetization rotation},
      journal={Physical Review Research},
      year={2019},
      volume={1},
      number={3},
      doi={10.1103/PhysRevResearch.1.032044},
      art_number={032044},
      note={cited By 29},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85078269419&doi=10.1103%2fPhysRevResearch.1.032044&partnerID=40&md5=135295b958867dd811bb033f2a6741d3},
      affiliation={Institute for Theoretical Solid State Physics, Ifw Dresden, Helmholtzstrasse 20, Dresden, 01069, Germany; Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, 44613, Nepal; Condensed Matter Physics Research Center, Butwal-11, Rupandehi, Nepal; Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, United States; Department of Physics, Harvard University, Cambridge, MA 02138, United States; John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States; Dresden Center for Computational Materials Science (DCMS), Tu Dresden, Dresden, 01069, Germany},
      abstract={As they do not rely on the presence of any crystal symmetry, Weyl nodes are robust topological features of an electronic structure that can occur at any momentum and energy. Acting as sinks and sources of Berry curvature, Weyl nodes have been predicted to strongly affect the transverse electronic response, like in the anomalous Hall or Nernst effects. However, to observe large anomalous effects the Weyl nodes need to be close to or at the Fermi level, which implies the band structure must be tuned by an external parameter, e.g., chemical doping. Here we show that in a ferromagnetic metal tuning of the Weyl node energy and momentum can be achieved by rotation of the magnetization. First, taking as example the elementary magnet hcp-Co, we use electronic structure calculations based on density-functional theory to show that by canting the magnetization away from the easy axis, Weyl nodes can be driven exactly to the Fermi surface. Second, we show that the same phenomenology applies to the kagome ferromagnet Co3Sn2S2, in which we additionally show how the dynamics in energy and momentum of the Weyl nodes affects the calculated anomalous Hall and Nernst conductivities. Our results highlight how the intrinsic magnetic anisotropy can be used to engineer Weyl physics. © 2019 authors. Published by the American Physical Society.},
      keywords={Crystal symmetry; Density functional theory; Electronic structure; Ferromagnetic materials; Ferromagnetism; Magnetic anisotropy; Magnets; Momentum, Anomalous effects; Chemical doping; Electronic structure calculations; Ferromagnets; Magnetization rotations; Nernst effect; Node energy; Topological features, Magnetization},
      publisher={American Physical Society},
      issn={26431564},
      language={English},
      abbrev_source_title={Phys. Rev. Res.},
      document_type={Article},
      source={Scopus},
      }

  • Templated dewetting of single-crystal sub-millimeter-long nanowires and on-chip silicon circuits
    • M. Bollani, M. Salvalaglio, A. Benali, M. Bouabdellaoui, M. Naffouti, M. Lodari, S. D. Corato, A. Fedorov, A. Voigt, I. Fraj, L. Favre, J. B. Claude, D. Grosso, G. Nicotra, A. Mio, A. Ronda, I. Berbezier, M. Abbarchi
    • Nature Communications 10, 5632 (2019)
    • DOI   Abstract  

      Large-scale, defect-free, micro- and nano-circuits with controlled inter-connections represent the nexus between electronic and photonic components. However, their fabrication over large scales often requires demanding procedures that are hardly scalable. Here we synthesize arrays of parallel ultra-long (up to 0.75 mm), monocrystalline, silicon-based nano-wires and complex, connected circuits exploiting low-resolution etching and annealing of thin silicon films on insulator. Phase field simulations reveal that crystal faceting and stabilization of the wires against breaking is due to surface energy anisotropy. Wires splitting, inter-connections and direction are independently managed by engineering the dewetting fronts and exploiting the spontaneous formation of kinks. Finally, we fabricate field-effect transistors with state-of-the-art trans-conductance and electron mobility. Beyond the first experimental evidence of controlled dewetting of patches featuring a record aspect ratio of ~ 1/60000 and self-assembled ~ mm long nano-wires, our method constitutes a distinct and promising approach for the deterministic implementation of atomically-smooth, mono-crystalline electronic and photonic circuits. © 2019, The Author(s).

      @ARTICLE{Bollani2019,
      author={Bollani, M. and Salvalaglio, M. and Benali, A. and Bouabdellaoui, M. and Naffouti, M. and Lodari, M. and Corato, S.D. and Fedorov, A. and Voigt, A. and Fraj, I. and Favre, L. and Claude, J.B. and Grosso, D. and Nicotra, G. and Mio, A. and Ronda, A. and Berbezier, I. and Abbarchi, M.},
      title={Templated dewetting of single-crystal sub-millimeter-long nanowires and on-chip silicon circuits},
      journal={Nature Communications},
      year={2019},
      volume={10},
      number={1},
      doi={10.1038/s41467-019-13371-3},
      art_number={5632},
      note={cited By 19},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076404860&doi=10.1038%2fs41467-019-13371-3&partnerID=40&md5=564823e6155ab37e22a4cdcc0d98931c},
      affiliation={Istituto di Fotonica e Nanotecnologie-Consiglio Nazionale delle Ricerche, Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, LNESS, Via Anzani 42, Como, 22100, Italy; Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Aix Marseille Univ, Université de Toulon, CNRS, Marseille, IM2NP, France; Laboratory of Physics of Condensed Matter and Renewable Energy, Faculty of Sciences and Technology, Hassan II University of Casablanca, 146 Mohammedia, Casablanca, Morocco; Laboratoire de Micro-Optoélectronique et Nanostructures, Faculté des Sciences de Monastir, Université de Monastir, Monastir, 5019, Tunisia; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; CNR-IMM, Zona Industriale Strada VIII, 5, Catania, 95121, Italy},
      abstract={Large-scale, defect-free, micro- and nano-circuits with controlled inter-connections represent the nexus between electronic and photonic components. However, their fabrication over large scales often requires demanding procedures that are hardly scalable. Here we synthesize arrays of parallel ultra-long (up to 0.75 mm), monocrystalline, silicon-based nano-wires and complex, connected circuits exploiting low-resolution etching and annealing of thin silicon films on insulator. Phase field simulations reveal that crystal faceting and stabilization of the wires against breaking is due to surface energy anisotropy. Wires splitting, inter-connections and direction are independently managed by engineering the dewetting fronts and exploiting the spontaneous formation of kinks. Finally, we fabricate field-effect transistors with state-of-the-art trans-conductance and electron mobility. Beyond the first experimental evidence of controlled dewetting of patches featuring a record aspect ratio of ~ 1/60000 and self-assembled ~ mm long nano-wires, our method constitutes a distinct and promising approach for the deterministic implementation of atomically-smooth, mono-crystalline electronic and photonic circuits. © 2019, The Author(s).},
      keywords={metal complex; nanowire; silicon, computer; crystal structure; electron; electronic equipment; energetics; etching, anisotropy; Article; biomedical engineering; computer simulation; crystal structure; crystallography; electric conductivity; electron; image analysis; materials science; nonhuman; scanning electron microscopy; scanning transmission electron microscopy; temperature},
      correspondence_address1={Bollani, M.; Istituto di Fotonica e Nanotecnologie-Consiglio Nazionale delle Ricerche, Via Anzani 42, Italy; email: monica.bollani@ifn.cnr.it},
      publisher={Nature Research},
      issn={20411723},
      pubmed_id={31822679},
      language={English},
      abbrev_source_title={Nat. Commun.},
      document_type={Article},
      source={Scopus},
      }

  • Stacks of Azobenzene Stars: Self-Assembly Scenario and Stabilising Forces Quantified in Computer Modelling
    • V. Savchenko, M. Koch, A. S. Pavlov, M. Saphiannikova, O. Guskova
    • Molecules 24, 4387 (2019)
    • DOI   Abstract  

      In this paper, the columnar supramolecular aggregates of photosensitive star-shaped azobenzenes with benzene-1,3,5-tricarboxamide core and azobenzene arms are analyzed theoretically by applying a combination of computer simulation techniques. Without a light stimulus, the azobenzene arms adopt the trans-state and build one-dimensional columns of stacked molecules during the first stage of the noncovalent association. These columnar aggregates represent the structural elements of more complex experimentally observed morphologies—fibers, spheres, gels, and others. Here, we determine the most favorable mutual orientations of the trans-stars in the stack in terms of (i) the π–π distance between the cores lengthwise the aggregate, (ii) the lateral displacements due to slippage and (iii) the rotation promoting the helical twist and chirality of the aggregate. To this end, we calculate the binding energy diagrams using density functional theory. The model predictions are further compared with available experimental data. The intermolecular forces responsible for the stability of the stacks in crystals are quantified using Hirshfeld surface analysis. Finally, to characterize the self-assembly mechanism of the stars in solution, we calculate the hydrogen bond lengths, the normalized dipole moments and the binding energies as functions of the columnar length. For this, molecular dynamics trajectories are analyzed. Finally, we conclude about the cooperative nature of the self-assembly of star-shaped azobenzenes with benzene-1,3,5-tricarboxamide core in aqueous solution. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

      @ARTICLE{Savchenko2019,
      author={Savchenko, V. and Koch, M. and Pavlov, A.S. and Saphiannikova, M. and Guskova, O.},
      title={Stacks of Azobenzene Stars: Self-Assembly Scenario and Stabilising Forces Quantified in Computer Modelling},
      journal={Molecules},
      year={2019},
      volume={24},
      number={23},
      doi={10.3390/molecules24234387},
      art_number={4387},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076144209&doi=10.3390%2fmolecules24234387&partnerID=40&md5=9dd3baed603fe54554c78ce6df9e37e4},
      affiliation={Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Department of Physical Chemistry, Faculty of Chemistry and Technology, Tver State University, Sadovyj per. 35, Tver, 170002, Russian Federation},
      abstract={In this paper, the columnar supramolecular aggregates of photosensitive star-shaped azobenzenes with benzene-1,3,5-tricarboxamide core and azobenzene arms are analyzed theoretically by applying a combination of computer simulation techniques. Without a light stimulus, the azobenzene arms adopt the trans-state and build one-dimensional columns of stacked molecules during the first stage of the noncovalent association. These columnar aggregates represent the structural elements of more complex experimentally observed morphologies—fibers, spheres, gels, and others. Here, we determine the most favorable mutual orientations of the trans-stars in the stack in terms of (i) the π–π distance between the cores lengthwise the aggregate, (ii) the lateral displacements due to slippage and (iii) the rotation promoting the helical twist and chirality of the aggregate. To this end, we calculate the binding energy diagrams using density functional theory. The model predictions are further compared with available experimental data. The intermolecular forces responsible for the stability of the stacks in crystals are quantified using Hirshfeld surface analysis. Finally, to characterize the self-assembly mechanism of the stars in solution, we calculate the hydrogen bond lengths, the normalized dipole moments and the binding energies as functions of the columnar length. For this, molecular dynamics trajectories are analyzed. Finally, we conclude about the cooperative nature of the self-assembly of star-shaped azobenzenes with benzene-1,3,5-tricarboxamide core in aqueous solution. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.},
      author_keywords={azobenzenes; computer simulations; cooperativity; hydrogen bonding; self-assembly},
      keywords={azo compound; azobenzene, algorithm; chemical model; chemical structure; chemistry; conformation; hydrogen bond; molecular dynamics, Algorithms; Azo Compounds; Hydrogen Bonding; Models, Chemical; Molecular Conformation; Molecular Dynamics Simulation; Molecular Structure},
      correspondence_address1={Guskova, O.; Dresden Center for Computational Materials Science (DCMS), Germany; email: guskova@ipfdd.de},
      publisher={MDPI},
      issn={14203049},
      coden={MOLEF},
      pubmed_id={31801297},
      language={English},
      abbrev_source_title={Molecules},
      document_type={Article},
      source={Scopus},
      }

  • Impact of molecular quadrupole moments on the energy levels at organic heterojunctions
    • M. Schwarze, K. S. Schellhammer, K. Ortstein, J. Benduhn, C. Gaul, A. Hinderhofer, L. Perdigón Toro, R. Scholz, J. Kublitski, S. Roland, M. Lau, C. Poelking, D. Andrienko, G. Cuniberti, F. Schreiber, D. Neher, K. Vandewal, F. Ortmann, K. Leo
    • Nature Communications 10, 2466 (2019)
    • DOI   Abstract  

      The functionality of organic semiconductor devices crucially depends on molecular energies, namely the ionisation energy and the electron affinity. Ionisation energy and electron affinity values of thin films are, however, sensitive to film morphology and composition, making their prediction challenging. In a combined experimental and simulation study on zinc-phthalocyanine and its fluorinated derivatives, we show that changes in ionisation energy as a function of molecular orientation in neat films or mixing ratio in blends are proportional to the molecular quadrupole component along the π-π-stacking direction. We apply these findings to organic solar cells and demonstrate how the electrostatic interactions can be tuned to optimise the energy of the charge-transfer state at the donor−acceptor interface and the dissociation barrier for free charge carrier generation. The confirmation of the correlation between interfacial energies and quadrupole moments for other materials indicates its relevance for small molecules and polymers. © 2019, The Author(s).

      @ARTICLE{Schwarze2019,
      author={Schwarze, M. and Schellhammer, K.S. and Ortstein, K. and Benduhn, J. and Gaul, C. and Hinderhofer, A. and Perdigón Toro, L. and Scholz, R. and Kublitski, J. and Roland, S. and Lau, M. and Poelking, C. and Andrienko, D. and Cuniberti, G. and Schreiber, F. and Neher, D. and Vandewal, K. and Ortmann, F. and Leo, K.},
      title={Impact of molecular quadrupole moments on the energy levels at organic heterojunctions},
      journal={Nature Communications},
      year={2019},
      volume={10},
      number={1},
      doi={10.1038/s41467-019-10435-2},
      art_number={2466},
      note={cited By 60},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066933035&doi=10.1038%2fs41467-019-10435-2&partnerID=40&md5=a01097f7ffffb2ae99e7ca40cb0c1de5},
      affiliation={Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Technische Universität Dresden, Dresden, 01069, Germany; Institute for Materials Science, Max-Bergmann Center of Biomaterials and Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01069, Germany; Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, Tübingen, 72076, Germany; Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24–25, Potsdam, 14476, Germany; Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany; Instituut voor Materiaalonderzoek (IMO), Hasselt University, Wetenschapspark 1, Diepenbeek, 3590, Belgium},
      abstract={The functionality of organic semiconductor devices crucially depends on molecular energies, namely the ionisation energy and the electron affinity. Ionisation energy and electron affinity values of thin films are, however, sensitive to film morphology and composition, making their prediction challenging. In a combined experimental and simulation study on zinc-phthalocyanine and its fluorinated derivatives, we show that changes in ionisation energy as a function of molecular orientation in neat films or mixing ratio in blends are proportional to the molecular quadrupole component along the π-π-stacking direction. We apply these findings to organic solar cells and demonstrate how the electrostatic interactions can be tuned to optimise the energy of the charge-transfer state at the donor−acceptor interface and the dissociation barrier for free charge carrier generation. The confirmation of the correlation between interfacial energies and quadrupole moments for other materials indicates its relevance for small molecules and polymers. © 2019, The Author(s).},
      keywords={fullerene; phthalocyanine zinc, electron; energy; film; ionization; mixing ratio; molecular analysis; morphology; orientation; photovoltaic system; prediction, Article; chemical structure; conformational transition; crystal structure; crystallization; density functional theory; energy; energy transfer; fluorescence resonance energy transfer; fluorination; galvanic current; ionization; isomer; light intensity; luminescence; magnetic field; molecular imaging; polarization; radiation scattering; simulation; static electricity; ultraviolet photoelectron spectroscopy; X ray diffraction},
      correspondence_address1={Schwarze, M.; Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Germany; email: Martin.Schwarze1@tu-dresden.de},
      publisher={Nature Publishing Group},
      issn={20411723},
      pubmed_id={31165738},
      language={English},
      abbrev_source_title={Nat. Commun.},
      document_type={Article},
      source={Scopus},
      }

  • Tuning the charge flow between Marcus regimes in an organic thin-film device
    • A. Atxabal, T. Arnold, S. Parui, S. Hutsch, E. Zuccatti, R. Llopis, M. Cinchetti, F. Casanova, F. Ortmann, L. E. Hueso
    • Nature Communications 10, 2089 (2019)
    • DOI   Abstract  

      Marcus’s theory of electron transfer, initially formulated six decades ago for redox reactions in solution, is now of great importance for very diverse scientific communities. The molecular scale tunability of electronic properties renders organic semiconductor materials in principle an ideal platform to test this theory. However, the demonstration of charge transfer in different Marcus regions requires a precise control over the driving force acting on the charge carriers. Here, we make use of a three-terminal hot-electron molecular transistor, which lets us access unconventional transport regimes. Thanks to the control of the injection energy of hot carriers in the molecular thin film we induce an effective negative differential resistance state that is a direct consequence of the Marcus Inverted Region. © 2019, The Author(s).

      @ARTICLE{Atxabal2019,
      author={Atxabal, A. and Arnold, T. and Parui, S. and Hutsch, S. and Zuccatti, E. and Llopis, R. and Cinchetti, M. and Casanova, F. and Ortmann, F. and Hueso, L.E.},
      title={Tuning the charge flow between Marcus regimes in an organic thin-film device},
      journal={Nature Communications},
      year={2019},
      volume={10},
      number={1},
      doi={10.1038/s41467-019-10114-2},
      art_number={2089},
      note={cited By 22},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065321068&doi=10.1038%2fs41467-019-10114-2&partnerID=40&md5=b8305a62b43453461e0a07fc3921b7cb},
      affiliation={CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain; Center for Advancing Electronics Dresden and Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; Experimentelle Physik VI, Technische Universität Dortmund, Dortmund, 44221, Germany; IKERBASQUE, Basque Foundation for Science, Bilbao, Basque Country, 48013, Spain; Simbeyond B. V., Eindhoven, AE 5612, Netherlands; IMEC, Kapeldreef 75, Leuven, 3001, Belgium; K. U. Leuven, Arenbergpark 10, Leuven, 3001, Belgium},
      abstract={Marcus’s theory of electron transfer, initially formulated six decades ago for redox reactions in solution, is now of great importance for very diverse scientific communities. The molecular scale tunability of electronic properties renders organic semiconductor materials in principle an ideal platform to test this theory. However, the demonstration of charge transfer in different Marcus regions requires a precise control over the driving force acting on the charge carriers. Here, we make use of a three-terminal hot-electron molecular transistor, which lets us access unconventional transport regimes. Thanks to the control of the injection energy of hot carriers in the molecular thin film we induce an effective negative differential resistance state that is a direct consequence of the Marcus Inverted Region. © 2019, The Author(s).},
      keywords={aluminum; aluminum oxide; boron; fullerene; nitrogen, electron; film; instrumentation; molecular analysis, Article; atomic force microscopy; electricity; electron; electron transport; evaporation; ion therapy; optical density; oxidation reduction reaction; temperature; X ray diffraction},
      correspondence_address1={Hueso, L.E.; CIC nanoGUNE, Spain; email: l.hueso@nanogune.eu},
      publisher={Nature Publishing Group},
      issn={20411723},
      pubmed_id={31064992},
      language={English},
      abbrev_source_title={Nat. Commun.},
      document_type={Article},
      source={Scopus},
      }

  • Closing the gap between atomic-scale lattice deformations and continuum elasticity
    • M. Salvalaglio, A. Voigt, K. R. Elder
    • npj Computational Materials 5, 48 (2019)
    • DOI   Abstract  

      Crystal lattice deformations can be described microscopically by explicitly accounting for the position of atoms or macroscopically by continuum elasticity. In this work, we report on the description of continuous elastic fields derived from an atomistic representation of crystalline structures that also include features typical of the microscopic scale. Analytic expressions for strain components are obtained from the complex amplitudes of the Fourier modes representing periodic lattice positions, which can be generally provided by atomistic modeling or experiments. The magnitude and phase of these amplitudes, together with the continuous description of strains, are able to characterize crystal rotations, lattice deformations, and dislocations. Moreover, combined with the so-called amplitude expansion of the phase-field crystal model, they provide a suitable tool for bridging microscopic to macroscopic scales. This study enables the in-depth analysis of elasticity effects for macroscale and mesoscale systems taking microscopic details into account. © 2019, The Author(s).

      @ARTICLE{Salvalaglio2019,
      author={Salvalaglio, M. and Voigt, A. and Elder, K.R.},
      title={Closing the gap between atomic-scale lattice deformations and continuum elasticity},
      journal={npj Computational Materials},
      year={2019},
      volume={5},
      number={1},
      doi={10.1038/s41524-019-0185-0},
      art_number={48},
      note={cited By 21},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064241842&doi=10.1038%2fs41524-019-0185-0&partnerID=40&md5=eacd101c78c0e78ffe4b7d0daac7ed85},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Department of Physics, Oakland University, Rochester, MI 48309, United States},
      abstract={Crystal lattice deformations can be described microscopically by explicitly accounting for the position of atoms or macroscopically by continuum elasticity. In this work, we report on the description of continuous elastic fields derived from an atomistic representation of crystalline structures that also include features typical of the microscopic scale. Analytic expressions for strain components are obtained from the complex amplitudes of the Fourier modes representing periodic lattice positions, which can be generally provided by atomistic modeling or experiments. The magnitude and phase of these amplitudes, together with the continuous description of strains, are able to characterize crystal rotations, lattice deformations, and dislocations. Moreover, combined with the so-called amplitude expansion of the phase-field crystal model, they provide a suitable tool for bridging microscopic to macroscopic scales. This study enables the in-depth analysis of elasticity effects for macroscale and mesoscale systems taking microscopic details into account. © 2019, The Author(s).},
      keywords={Elasticity; Fourier series; Strain, Amplitude expansion; Analytic expressions; Atomistic representation; Continuum elasticity; Crystal lattice deformation; Crystalline structure; Lattice deformation; Phase field crystal model, Deformation},
      correspondence_address1={Salvalaglio, M.; Institute of Scientific Computing, Germany; email: marco.salvalaglio@tu-dresden.de},
      publisher={Nature Publishing Group},
      issn={20573960},
      language={English},
      abbrev_source_title={npj Computational Mater.},
      document_type={Article},
      source={Scopus},
      }

  • Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal–metal bond
    • F. Liu, G. Velkos, D. S. Krylov, L. Spree, M. Zalibera, R. Ray, N. A. Samoylova, C. -H. Chen, M. Rosenkranz, S. Schiemenz, F. Ziegs, K. Nenkov, A. Kostanyan, T. Greber, A. U. B. Wolter, M. Richter, B. Büchner, S. M. Avdoshenko, A. A. Popov
    • Nature Communications 10, 571 (2019)
    • DOI   Abstract  

      Engineering intramolecular exchange interactions between magnetic metal atoms is a ubiquitous strategy for designing molecular magnets. For lanthanides, the localized nature of 4f electrons usually results in weak exchange coupling. Mediating magnetic interactions between lanthanide ions via radical bridges is a fruitful strategy towards stronger coupling. In this work we explore the limiting case when the role of a radical bridge is played by a single unpaired electron. We synthesize an array of air-stable Ln 2 @C 80 (CH 2 Ph) dimetallofullerenes (Ln 2 = Y 2 , Gd 2 , Tb 2 , Dy 2 , Ho 2 , Er 2 , TbY, TbGd) featuring a covalent lanthanide-lanthanide bond. The lanthanide spins are glued together by very strong exchange interactions between 4f moments and a single electron residing on the metal–metal bonding orbital. Tb 2 @C 80 (CH 2 Ph) shows a gigantic coercivity of 8.2 Tesla at 5 K and a high 100-s blocking temperature of magnetization of 25.2 K. The Ln-Ln bonding orbital in Ln 2 @C 80 (CH 2 Ph) is redox active, enabling electrochemical tuning of the magnetism. © 2019, The Author(s).

      @ARTICLE{Liu2019,
      author={Liu, F. and Velkos, G. and Krylov, D.S. and Spree, L. and Zalibera, M. and Ray, R. and Samoylova, N.A. and Chen, C.-H. and Rosenkranz, M. and Schiemenz, S. and Ziegs, F. and Nenkov, K. and Kostanyan, A. and Greber, T. and Wolter, A.U.B. and Richter, M. and Büchner, B. and Avdoshenko, S.M. and Popov, A.A.},
      title={Air-stable redox-active nanomagnets with lanthanide spins radical-bridged by a metal–metal bond},
      journal={Nature Communications},
      year={2019},
      volume={10},
      number={1},
      doi={10.1038/s41467-019-08513-6},
      art_number={571},
      note={cited By 74},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061050303&doi=10.1038%2fs41467-019-08513-6&partnerID=40&md5=394ab0fa0238c7d120442199e0a6c3d4},
      affiliation={Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstrasse 20, Dresden, 01069, Germany; Institute of Physical Chemistry and Chemical Physics, Slovak University of Technology, Radlinského 9, Bratislava, 81237, Slovakia; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, D-01062, Germany; Physik-Institut der Universität Zürich, Winterthurerstrasse 190, Zürich, CH-8057, Switzerland},
      abstract={Engineering intramolecular exchange interactions between magnetic metal atoms is a ubiquitous strategy for designing molecular magnets. For lanthanides, the localized nature of 4f electrons usually results in weak exchange coupling. Mediating magnetic interactions between lanthanide ions via radical bridges is a fruitful strategy towards stronger coupling. In this work we explore the limiting case when the role of a radical bridge is played by a single unpaired electron. We synthesize an array of air-stable Ln 2 @C 80 (CH 2 Ph) dimetallofullerenes (Ln 2 = Y 2 , Gd 2 , Tb 2 , Dy 2 , Ho 2 , Er 2 , TbY, TbGd) featuring a covalent lanthanide-lanthanide bond. The lanthanide spins are glued together by very strong exchange interactions between 4f moments and a single electron residing on the metal–metal bonding orbital. Tb 2 @C 80 (CH 2 Ph) shows a gigantic coercivity of 8.2 Tesla at 5 K and a high 100-s blocking temperature of magnetization of 25.2 K. The Ln-Ln bonding orbital in Ln 2 @C 80 (CH 2 Ph) is redox active, enabling electrochemical tuning of the magnetism. © 2019, The Author(s).},
      keywords={dysprosium; erbium; gadolinium; holmium; lanthanide; metal; nanoparticle; radical; terbium, air; Article; chemical bond; electron; magnetism; metal binding; molecular interaction; molecular stability; oxidation reduction reaction; synthesis},
      correspondence_address1={Liu, F.; Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstrasse 20, Germany; email: f.liu@ifw-dresden.de},
      publisher={Nature Publishing Group},
      issn={20411723},
      pubmed_id={30718550},
      language={English},
      abbrev_source_title={Nat. Commun.},
      document_type={Article},
      source={Scopus},
      }

  • Do Columns of Azobenzene Stars Disassemble under Light Illumination?
    • M. Koch, M. Saphiannikova, O. Guskova
    • Langmuir 35, 14659-14669 (2019)
    • DOI   Abstract  

      The clustering properties of star-shaped molecules comprising three photochromic azobenzene-containing arms are investigated with specific focus on the influence of light on these structures. Previous experimental works report self-assembly of azobenzene stars in aqueous solution into long columnar clusters that are detectable using optical microscopy. These clusters appear to vanish under UV irradiation, which is known to induce trans-to-cis photoisomerization of the azobenzene groups. We have performed MD simulations, density functional theory, and density functional tight binding calculations to determine conformational properties and binding energies of these clusters. Our simulation data suggest that the binding strength of the clusters is large enough to prevent a breaking along their main axis. We conclude that very likely other mechanisms lead to the apparent disappearance of the clusters. Copyright © 2019 American Chemical Society.

      @ARTICLE{Koch201914659,
      author={Koch, M. and Saphiannikova, M. and Guskova, O.},
      title={Do Columns of Azobenzene Stars Disassemble under Light Illumination?},
      journal={Langmuir},
      year={2019},
      volume={35},
      number={45},
      pages={14659-14669},
      doi={10.1021/acs.langmuir.9b02960},
      note={cited By 7},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074614079&doi=10.1021%2facs.langmuir.9b02960&partnerID=40&md5=485eb361f6e6f52349ff0c5d06c02598},
      affiliation={Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={The clustering properties of star-shaped molecules comprising three photochromic azobenzene-containing arms are investigated with specific focus on the influence of light on these structures. Previous experimental works report self-assembly of azobenzene stars in aqueous solution into long columnar clusters that are detectable using optical microscopy. These clusters appear to vanish under UV irradiation, which is known to induce trans-to-cis photoisomerization of the azobenzene groups. We have performed MD simulations, density functional theory, and density functional tight binding calculations to determine conformational properties and binding energies of these clusters. Our simulation data suggest that the binding strength of the clusters is large enough to prevent a breaking along their main axis. We conclude that very likely other mechanisms lead to the apparent disappearance of the clusters. Copyright © 2019 American Chemical Society.},
      keywords={Azobenzene; Binding energy; Irradiation; Stars, Azobenzene group; Clustering properties; Columnar clusters; Conformational properties; Density functional tight bindings; Light illumination; Photochromic azobenzene; Star-shaped molecules, Density functional theory},
      correspondence_address1={Guskova, O.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: guskova@ipfdd.de},
      publisher={American Chemical Society},
      issn={07437463},
      coden={LANGD},
      pubmed_id={31627699},
      language={English},
      abbrev_source_title={Langmuir},
      document_type={Article},
      source={Scopus},
      }

  • Chirality-Induced Spin Selectivity in a Coarse-Grained Tight-Binding Model for Helicene
    • M. Geyer, R. Gutierrez, V. Mujica, G. Cuniberti
    • Journal of Physical Chemistry C 123, 27230-27241 (2019)
    • DOI   Abstract  

      Spin-dependent effects in helical molecular systems, leading to the so-called chirality-induced spin selectivity (CISS) effect, have strongly attracted the attention of the chemical and physical community over the past few years. A large amount of experimental material has been collected so far, and different theoretical approaches have been presented to rationalize the CISS effect. The problem is, however, still a subject of debate. We present a semianalytical coarse-grained atomistic description of the electronic structure of a simple helical molecule, including spin-orbit interactions. For reference, we consider helicene, which is a pure carbon-based helical system with no chiral centers, and which has been previously shown experimentally to display a CISS effect. Our model exploits perturbation theory and a Löwdin-like partitioning to obtain an effective Ï-πHamiltonian, where all coupling coefficients depend on the helical geometry and predefined Slater-Koster parameters. As a result, they can be explicitly computed, thus providing physically meaningful orders of magnitude. We further discuss the conditions under which a nonvanishing spin polarization can be obtained in the model. We expect that our approach will serve to bridge the gap between purely phenomenological model Hamiltonians and more advanced first-principles methodologies. © 2019 American Chemical Society.

      @ARTICLE{Geyer201927230,
      author={Geyer, M. and Gutierrez, R. and Mujica, V. and Cuniberti, G.},
      title={Chirality-Induced Spin Selectivity in a Coarse-Grained Tight-Binding Model for Helicene},
      journal={Journal of Physical Chemistry C},
      year={2019},
      volume={123},
      number={44},
      pages={27230-27241},
      doi={10.1021/acs.jpcc.9b07764},
      note={cited By 32},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074425094&doi=10.1021%2facs.jpcc.9b07764&partnerID=40&md5=bee32c668babece8f94d0f3060bbe43b},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, United States; Donostia International Physics Center, P.K. 1072, Donostia, Euskadi, 20080, Spain},
      abstract={Spin-dependent effects in helical molecular systems, leading to the so-called chirality-induced spin selectivity (CISS) effect, have strongly attracted the attention of the chemical and physical community over the past few years. A large amount of experimental material has been collected so far, and different theoretical approaches have been presented to rationalize the CISS effect. The problem is, however, still a subject of debate. We present a semianalytical coarse-grained atomistic description of the electronic structure of a simple helical molecule, including spin-orbit interactions. For reference, we consider helicene, which is a pure carbon-based helical system with no chiral centers, and which has been previously shown experimentally to display a CISS effect. Our model exploits perturbation theory and a Löwdin-like partitioning to obtain an effective Ï-πHamiltonian, where all coupling coefficients depend on the helical geometry and predefined Slater-Koster parameters. As a result, they can be explicitly computed, thus providing physically meaningful orders of magnitude. We further discuss the conditions under which a nonvanishing spin polarization can be obtained in the model. We expect that our approach will serve to bridge the gap between purely phenomenological model Hamiltonians and more advanced first-principles methodologies. © 2019 American Chemical Society.},
      keywords={Chirality; Electronic structure; Perturbation techniques; Spin polarization, Coupling coefficient; Experimental materials; Orders of magnitude; Perturbation theory; Phenomenological modeling; Spin orbit interactions; Spin-dependent effects; Theoretical approach, Stereochemistry},
      correspondence_address1={Geyer, M.; Institute for Materials Science, Germany; email: matthias.geyer@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19327447},
      language={English},
      abbrev_source_title={J. Phys. Chem. C},
      document_type={Article},
      source={Scopus},
      }

  • An improved Green’s function algorithm applied to quantum transport in carbon nanotubes
    • F. Teichert, A. Zienert, J. Schuster, M. Schreiber
    • Computational Materials Science 169, 109014 (2019)
    • DOI   Abstract  

      The renormalization-decimation algorithm (RDA) of López Sancho et al. is used in quantum transport theory to calculate bulk and surface Green’s functions. We derive an improved version of the RDA for the case of very long quasi one-dimensional unit cells (in transport direction). This covers not only long unit cells but also supercell-like calculations for structures with disorder or defects. In such large systems, short-range interactions lead to sparse real-space Hamiltonian matrices. We show how this and a corresponding subdivision of the unit cell in combination with the decimation technique can be used to reduce the calculation time. Within the resulting algorithm, separate RDA calculations of much smaller effective Hamiltonian matrices must be done for each Green’s function, which enables the treatment of systems too large for the common RDA. Finally, we discuss the performance properties of our improved algorithm as well as some exemplary results for chiral carbon nanotubes. © 2019 Elsevier B.V.

      @ARTICLE{Teichert2019,
      author={Teichert, F. and Zienert, A. and Schuster, J. and Schreiber, M.},
      title={An improved Green's function algorithm applied to quantum transport in carbon nanotubes},
      journal={Computational Materials Science},
      year={2019},
      volume={169},
      doi={10.1016/j.commatsci.2019.05.012},
      art_number={109014},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070532970&doi=10.1016%2fj.commatsci.2019.05.012&partnerID=40&md5=75f2e03dd4d7ec0fdb6138470a54e653},
      affiliation={Institute of Physics, Chemnitz University of Technology, Chemnitz, 09107, Germany; Center for Microtechnologies, Chemnitz University of Technology, Chemnitz, 09107, Germany; Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz, 09126, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={The renormalization-decimation algorithm (RDA) of López Sancho et al. is used in quantum transport theory to calculate bulk and surface Green's functions. We derive an improved version of the RDA for the case of very long quasi one-dimensional unit cells (in transport direction). This covers not only long unit cells but also supercell-like calculations for structures with disorder or defects. In such large systems, short-range interactions lead to sparse real-space Hamiltonian matrices. We show how this and a corresponding subdivision of the unit cell in combination with the decimation technique can be used to reduce the calculation time. Within the resulting algorithm, separate RDA calculations of much smaller effective Hamiltonian matrices must be done for each Green's function, which enables the treatment of systems too large for the common RDA. Finally, we discuss the performance properties of our improved algorithm as well as some exemplary results for chiral carbon nanotubes. © 2019 Elsevier B.V.},
      author_keywords={Carbon nanotube (CNT); Electronic transport; Renormalization-decimation algorithm (RDA)},
      keywords={Hamiltonians; Quantum chemistry; Statistical mechanics, Effective Hamiltonian; Electronic transport; Hamiltonian matrix; Performance properties; Quasi-one dimensional; Renormalization; Short range interactions; Transport direction, Carbon nanotubes},
      correspondence_address1={Teichert, F.; Institute of Physics, Germany; email: fabian.teichert@physik.tu-chemnitz.de},
      publisher={Elsevier B.V.},
      issn={09270256},
      coden={CMMSE},
      language={English},
      abbrev_source_title={Comput Mater Sci},
      document_type={Article},
      source={Scopus},
      }

  • Numerical and Experimental Study of the Spatial Stress Distribution on the Cornea Surface During a Non-Contact Tonometry Examination
    • S. Muench, M. Roellig, E. Spoerl, D. Balzani
    • Experimental Mechanics 59, 1285-1297 (2019)
    • DOI   Abstract  

      The determination of biomechanical properties of the cornea by a non-contact tonometry (NCT) examination requires a precise knowledge of the air puff generated in the device, which is applied to the cornea surface. In this study, a method is proposed to identify the resulting stress profile on the surface, which may be used to numerically solve an inverse problem to obtain the material properties. This method is based on an experimental characterization of the air puff created by the Corvis ST in combination with computational fluid dynamic (CFD) simulations, which are adjusted to the experimental data. The identified nozzle inlet pressure of approximately 25 kPa (188.5mmHg) is then used for a numerical influence study of the interaction between the air puff and the cornea deformation. Therefore, eleven cornea deformation states based on measurements are implemented in the CFD model. A more realistic model is also analyzed by the geometrical reproduction of the human face, which is used for a further influence study. The outcomes showed a dependence between the cornea deformation and the pressure as well as the shear stress distribution. However, quantitatively, the shear stress component can be considered of minor importance being approximately one hundred times smaller than the pressure. The examination with consideration of the human face demonstrates that the pressure and shear stress distributions are not rotationally symmetric in measurements on real humans, which indicates the requirement to include more complex stress distributions on the eye. We present the detailed stress distribution on the cornea during a non-contact tonometry examination, which is made accessible for further investigations in the future by analytical nonlinear functions. © 2018, Society for Experimental Mechanics.

      @ARTICLE{Muench20191285,
      author={Muench, S. and Roellig, M. and Spoerl, E. and Balzani, D.},
      title={Numerical and Experimental Study of the Spatial Stress Distribution on the Cornea Surface During a Non-Contact Tonometry Examination},
      journal={Experimental Mechanics},
      year={2019},
      volume={59},
      number={9},
      pages={1285-1297},
      doi={10.1007/s11340-018-00449-0},
      note={cited By 5},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058390192&doi=10.1007%2fs11340-018-00449-0&partnerID=40&md5=984b0e407ea5c2142edd819fc9848e3e},
      affiliation={Institute of Mechanics and Shell Structures (IMF), Dresden, 01062, Germany; Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), Dresden, 01109, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Department of Ophthalmology, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, Dresden, 01307, Germany; Chair of Computational Mechanics, Ruhr-Universität Bochum, Bochum, 44801, Germany},
      abstract={The determination of biomechanical properties of the cornea by a non-contact tonometry (NCT) examination requires a precise knowledge of the air puff generated in the device, which is applied to the cornea surface. In this study, a method is proposed to identify the resulting stress profile on the surface, which may be used to numerically solve an inverse problem to obtain the material properties. This method is based on an experimental characterization of the air puff created by the Corvis ST in combination with computational fluid dynamic (CFD) simulations, which are adjusted to the experimental data. The identified nozzle inlet pressure of approximately 25 kPa (188.5mmHg) is then used for a numerical influence study of the interaction between the air puff and the cornea deformation. Therefore, eleven cornea deformation states based on measurements are implemented in the CFD model. A more realistic model is also analyzed by the geometrical reproduction of the human face, which is used for a further influence study. The outcomes showed a dependence between the cornea deformation and the pressure as well as the shear stress distribution. However, quantitatively, the shear stress component can be considered of minor importance being approximately one hundred times smaller than the pressure. The examination with consideration of the human face demonstrates that the pressure and shear stress distributions are not rotationally symmetric in measurements on real humans, which indicates the requirement to include more complex stress distributions on the eye. We present the detailed stress distribution on the cornea during a non-contact tonometry examination, which is made accessible for further investigations in the future by analytical nonlinear functions. © 2018, Society for Experimental Mechanics.},
      author_keywords={Air puff characterization; Computational fluid dynamics; Corneal biomechanics; Non-contact tonometry; Pressure distribution; Shear force distribution},
      keywords={Air; Biomechanics; Deformation; Inverse problems; Pressure distribution; Shear stress; Stress analysis; Stress concentration, Air puffs; Biomechanical properties; Corneal biomechanics; Experimental characterization; Non-contact; Numerical and experimental study; Shear force distribution; Shear stress component, Computational fluid dynamics},
      correspondence_address1={Muench, S.; Institute of Mechanics and Shell Structures (IMF)Germany; email: stefan.muench@ikts.fraunhofer.de},
      publisher={Springer New York LLC},
      issn={00144851},
      coden={EXMCA},
      language={English},
      abbrev_source_title={Exp. Mech.},
      document_type={Article},
      source={Scopus},
      }

  • Large off-diagonal exchange couplings and spin liquid states in C3-symmetric iridates
    • R. Yadav, S. Nishimoto, M. Richter, J. Van Den Brink, R. Ray
    • Physical Review B 100, 144422 (2019)
    • DOI   Abstract  

      Iridate oxides on a honeycomb lattice are considered promising candidates for realization of quantum spin liquid states. We investigate the magnetic couplings in a structural model for a honeycomb iridate K2IrO3, with C3 point-group symmetry at the Ir sites, which is an end member of the recently synthesized iridate family KxIryO2. Using ab initio quantum chemical methods, we elucidate the subtle relationship between the real space symmetry and magnetic anisotropy and show that the higher point-group symmetry leads to high frustration with strong magnetic anisotropy driven by the unusually large off-diagonal exchange couplings (Γ’s) as opposed to other spin-liquid candidates considered so far. Consequently, large quantum fluctuations imply lack of magnetic ordering consistent with the experiments. Exact diagonalization calculations for the fully anisotropic K-J-Γ Hamiltonian reveal the importance of the off-diagonal anisotropic exchange couplings in stabilizing a spin liquid state and highlight an alternative route to stabilize spin liquid states for ferromagnetic K. © 2019 American Physical Society.

      @ARTICLE{Yadav2019,
      author={Yadav, R. and Nishimoto, S. and Richter, M. and Van Den Brink, J. and Ray, R.},
      title={Large off-diagonal exchange couplings and spin liquid states in C3-symmetric iridates},
      journal={Physical Review B},
      year={2019},
      volume={100},
      number={14},
      doi={10.1103/PhysRevB.100.144422},
      art_number={144422},
      note={cited By 8},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074432597&doi=10.1103%2fPhysRevB.100.144422&partnerID=40&md5=bd46df97e692dba56d336f0ee9af28ff},
      affiliation={IFW Dresden, Helmholtzstrasse 20, Dresden, D-01069, Germany; Department of Physics, TU Dresden, Dresden, D-01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, D-01062, Germany},
      abstract={Iridate oxides on a honeycomb lattice are considered promising candidates for realization of quantum spin liquid states. We investigate the magnetic couplings in a structural model for a honeycomb iridate K2IrO3, with C3 point-group symmetry at the Ir sites, which is an end member of the recently synthesized iridate family KxIryO2. Using ab initio quantum chemical methods, we elucidate the subtle relationship between the real space symmetry and magnetic anisotropy and show that the higher point-group symmetry leads to high frustration with strong magnetic anisotropy driven by the unusually large off-diagonal exchange couplings (Γ's) as opposed to other spin-liquid candidates considered so far. Consequently, large quantum fluctuations imply lack of magnetic ordering consistent with the experiments. Exact diagonalization calculations for the fully anisotropic K-J-Γ Hamiltonian reveal the importance of the off-diagonal anisotropic exchange couplings in stabilizing a spin liquid state and highlight an alternative route to stabilize spin liquid states for ferromagnetic K. © 2019 American Physical Society.},
      keywords={Calculations; Exchange coupling; Excitons; Honeycomb structures; Liquids; Magnetic anisotropy; Magnetism; Point groups; Quantum chemistry; Quantum theory, Ab initio quantum chemical methods; Anisotropic exchange; Exact diagonalization; Honeycomb lattices; Point group symmetry; Quantum fluctuation; Quantum spin liquid; Structural modeling, Magnetic couplings},
      publisher={American Physical Society},
      issn={24699950},
      language={English},
      abbrev_source_title={Phys. Rev. B},
      document_type={Article},
      source={Scopus},
      }

  • Deterministic three-dimensional self-assembly of Si through a rimless and topology-preserving dewetting regime
    • M. Naffouti, M. Salvalaglio, T. David, J. -B. Claude, M. Bollani, A. Voigt, A. Benkouider, L. Favre, A. Ronda, I. Berbezier, A. Delobbe, A. Houel, M. Abbarchi
    • Physical Review Materials 3, 103402 (2019)
    • DOI   Abstract  

      Capillary-driven mass transport in solids is typically understood in terms of surface-diffusion limited kinetics, leading to conventional solid-state dewetting of thin films. However, another mass transport mechanism, so-called surface-attachment/detachment limited kinetics, is possible. It can shrink a solid film, preserving its original topology without breaking it in isolated islands, and leads to faster dynamics for smaller film curvature in contrast with the opposite behavior observed for surface-diffusion limited kinetics. In this work, we present a rimless dewetting regime for Si, which is ascribed to effective attachment-limited kinetics mediated by the coexistence of crystalline and amorphous Si phases. Phase-field numerical simulations quantitatively reproduce the experimental observations, assessing the main mass transport mechanism at play. The process can be exploited to obtain in a deterministic fashion monocrystalline islands (with 95% probability) pinned at ≈500 nm from a hole milled within closed patches. © 2019 American Physical Society.

      @ARTICLE{Naffouti2019,
      author={Naffouti, M. and Salvalaglio, M. and David, T. and Claude, J.-B. and Bollani, M. and Voigt, A. and Benkouider, A. and Favre, L. and Ronda, A. and Berbezier, I. and Delobbe, A. and Houel, A. and Abbarchi, M.},
      title={Deterministic three-dimensional self-assembly of Si through a rimless and topology-preserving dewetting regime},
      journal={Physical Review Materials},
      year={2019},
      volume={3},
      number={10},
      doi={10.1103/PhysRevMaterials.3.103402},
      art_number={103402},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073456787&doi=10.1103%2fPhysRevMaterials.3.103402&partnerID=40&md5=fc34950d0caf7ae32d536d350f93055f},
      affiliation={Aix Marseille Université, Université de Toulon, CNRS, IM2NP, Marseille, France; Laboratoire de Micro-Optoélectronique et Nanostructures, Faculté des Sciences, Monastir Université de Monastir, Monastir, 5019, Tunisia; Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Istituto di Fotonica e Nanotecnologie-Consiglio Nazionale Delle Ricerche, Laboratory for Nanostructure Epitaxy and Spintronics on Silicon, Via Anzani 42, Como, 22100, Italy; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; Orsay Physics, Fuveau, 13710, France},
      abstract={Capillary-driven mass transport in solids is typically understood in terms of surface-diffusion limited kinetics, leading to conventional solid-state dewetting of thin films. However, another mass transport mechanism, so-called surface-attachment/detachment limited kinetics, is possible. It can shrink a solid film, preserving its original topology without breaking it in isolated islands, and leads to faster dynamics for smaller film curvature in contrast with the opposite behavior observed for surface-diffusion limited kinetics. In this work, we present a rimless dewetting regime for Si, which is ascribed to effective attachment-limited kinetics mediated by the coexistence of crystalline and amorphous Si phases. Phase-field numerical simulations quantitatively reproduce the experimental observations, assessing the main mass transport mechanism at play. The process can be exploited to obtain in a deterministic fashion monocrystalline islands (with 95% probability) pinned at ≈500 nm from a hole milled within closed patches. © 2019 American Physical Society.},
      keywords={Kinetics; Self assembly; Surface diffusion; Thin films; Topology, Amorphous Si; Capillary-driven mass transport; Isolated islands; Monocrystalline; Phase fields; Surface attachment; Topology preserving; Transport mechanism, Amorphous silicon},
      publisher={American Physical Society},
      issn={24759953},
      language={English},
      abbrev_source_title={Physic. Rev. Mat.},
      document_type={Article},
      source={Scopus},
      }

  • Towards reconfigurable electronics: Silicidation of top-down fabricated silicon nanowires
    • M. B. Khan, D. Deb, J. Kerbusch, F. Fuchs, M. Löffler, S. Banerjee, U. Mühle, W. M. Weber, S. Gemming, J. Schuster, A. Erbe, Y. M. Georgiev
    • Applied Sciences (Switzerland) 9, 3462 (2019)
    • DOI   Abstract  

      We present results of our investigations on nickel silicidation of top-down fabricated silicon nanowires (SiNWs). Control over the silicidation process is important for the application of SiNWs in reconfigurable field-effect transistors. Silicidation is performed using a rapid thermal annealing process on the SiNWs fabricated by electron beam lithography and inductively-coupled plasma etching. The effects of variations in crystallographic orientations of SiNWs and different NW designs on the silicidation process are studied. Scanning electron microscopy and transmission electron microscopy are performed to study Ni diffusion, silicide phases, and silicide-silicon interfaces. Control over the silicide phase is achieved together with atomically sharp silicide-silicon interfaces. We find that (111) interfaces are predominantly formed, which are energetically most favorable according to density functional theory calculations. However, control over the silicide length remains a challenge. © 2019 by the authors.

      @ARTICLE{Khan2019,
      author={Khan, M.B. and Deb, D. and Kerbusch, J. and Fuchs, F. and Löffler, M. and Banerjee, S. and Mühle, U. and Weber, W.M. and Gemming, S. and Schuster, J. and Erbe, A. and Georgiev, Y.M.},
      title={Towards reconfigurable electronics: Silicidation of top-down fabricated silicon nanowires},
      journal={Applied Sciences (Switzerland)},
      year={2019},
      volume={9},
      number={17},
      doi={10.3390/app9173462},
      art_number={3462},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85072286808&doi=10.3390%2fapp9173462&partnerID=40&md5=4ea9fddcb7650e0573fe0f703fd65541},
      affiliation={Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, 01328, Germany; International Helmholtz Research School for Nanoelectronic Network, HZDR, Dresden, 01328, Germany; Center for Advancing Electronics Dresden, Dresden University of Technology, Dresden, 01062, Germany; Institute of Physics, Chemnitz University of Technology, Chemitz, 09126, Germany; Fraunhofer Institute for Electronic Nano Systems, Chemnitz, 09126, Germany; Dresden Center for Nano-Analysis, Dresden University of Technology, Dresden, 01062, Germany; Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Dresden, Dresden, 01277, Germany; Namlab gGmbH, Nöthnitzer Strasse 64, Dresden, 01187, Germany; Dresden Center for Computational Materials Science, Dresden University of Technology, Dresden, 01062, Germany; On leave of absence from the Institute of Electronics, Bulgarian Academy of Sciences, 72, Tsarigradsko Chausse Blvd., Sofia, 1784, Bulgaria},
      abstract={We present results of our investigations on nickel silicidation of top-down fabricated silicon nanowires (SiNWs). Control over the silicidation process is important for the application of SiNWs in reconfigurable field-effect transistors. Silicidation is performed using a rapid thermal annealing process on the SiNWs fabricated by electron beam lithography and inductively-coupled plasma etching. The effects of variations in crystallographic orientations of SiNWs and different NW designs on the silicidation process are studied. Scanning electron microscopy and transmission electron microscopy are performed to study Ni diffusion, silicide phases, and silicide-silicon interfaces. Control over the silicide phase is achieved together with atomically sharp silicide-silicon interfaces. We find that (111) interfaces are predominantly formed, which are energetically most favorable according to density functional theory calculations. However, control over the silicide length remains a challenge. © 2019 by the authors.},
      author_keywords={Annealing; Field-effect transistors; Nickel silicide; Schottky junction},
      correspondence_address1={Khan, M.B.; Institute of Ion Beam Physics and Materials Research, Germany; email: m.khan@hzdr.de},
      publisher={MDPI AG},
      issn={20763417},
      language={English},
      abbrev_source_title={Appl. Sci.},
      document_type={Article},
      source={Scopus},
      }

  • Recapitulating bone development events in a customised bioreactor through interplay of oxygen tension, medium pH, and systematic differentiation approaches
    • P. S. Lee, R. Hess, J. Friedrichs, V. Haenchen, H. Eckert, G. Cuniberti, D. Rancourt, R. Krawetz, V. Hintze, M. Gelinsky, D. Scharnweber
    • Journal of Tissue Engineering and Regenerative Medicine 13, 1672-1684 (2019)
    • DOI   Abstract  

      Bone development and homeostasis are intricate processes that require co-existence and dynamic interactions among multiple cell types. However, controlled dynamic niches that derive and support stable propagation of these cells from single stem cell source is not sustainable in conventional culturing vessels. In bioreactor cultures that support dynamic niches, the limited source and stability of growth factors are often a major limiting factor for long-term in vitro cultures. Hence, alternative growth factor-free differentiation approaches are designed and their efficacy to achieve different osteochondral cell types is investigated. Briefly, a dynamic niche is achieved by varying medium pH, oxygen tension (pO2) distribution in bioreactor, initiating chondrogenic differentiation with chondroitin sulphate A (CSA), and implementing systematic differentiation regimes. In this study, we demonstrated that CSA is a potent chondrogenic inducer, specifically in combination with acidic medium and low pO2. Further, endochondral ossification is recapitulated through a systematic chondrogenic–osteogenic (ch-os) differentiation regime, and multiple osteochondral cell types are derived. Chondrogenic hypertrophy was also enhanced specifically in high pO2 regions. Consequently, mineralised constructs with higher structural integrity, volume, and tailored dimensions are achieved. In contrast, a continuous osteogenic differentiation regime (os-os) has derived compact and dense constructs, whereas a continuous chondrogenic differentiation regime (ch-ch) has attenuated construct mineralisation and impaired development. In conclusion, a growth factor-free differentiation approach is achieved through interplay of pO2, medium pH, and systematic differentiation regimes. The controlled dynamic niches have recapitulated endochondral ossification and can potentially be exploited to derive larger bone constructs with near physiological properties. © 2019 John Wiley & Sons, Ltd.

      @ARTICLE{Lee20191672,
      author={Lee, P.S. and Hess, R. and Friedrichs, J. and Haenchen, V. and Eckert, H. and Cuniberti, G. and Rancourt, D. and Krawetz, R. and Hintze, V. and Gelinsky, M. and Scharnweber, D.},
      title={Recapitulating bone development events in a customised bioreactor through interplay of oxygen tension, medium pH, and systematic differentiation approaches},
      journal={Journal of Tissue Engineering and Regenerative Medicine},
      year={2019},
      volume={13},
      number={9},
      pages={1672-1684},
      doi={10.1002/term.2921},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069914153&doi=10.1002%2fterm.2921&partnerID=40&md5=cde5d1947084e9e0b5647b56dd619166},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, Germany; Leibniz Institute of Polymer Research Dresden e. V., Dresden, Germany; Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, Germany; Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, Calgary, AB, Canada; Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, AB, Canada; Center for Translational Bone, Joint and Soft Tissue Research, Technische Universität Dresden, Dresden, Germany},
      abstract={Bone development and homeostasis are intricate processes that require co-existence and dynamic interactions among multiple cell types. However, controlled dynamic niches that derive and support stable propagation of these cells from single stem cell source is not sustainable in conventional culturing vessels. In bioreactor cultures that support dynamic niches, the limited source and stability of growth factors are often a major limiting factor for long-term in vitro cultures. Hence, alternative growth factor-free differentiation approaches are designed and their efficacy to achieve different osteochondral cell types is investigated. Briefly, a dynamic niche is achieved by varying medium pH, oxygen tension (pO2) distribution in bioreactor, initiating chondrogenic differentiation with chondroitin sulphate A (CSA), and implementing systematic differentiation regimes. In this study, we demonstrated that CSA is a potent chondrogenic inducer, specifically in combination with acidic medium and low pO2. Further, endochondral ossification is recapitulated through a systematic chondrogenic–osteogenic (ch-os) differentiation regime, and multiple osteochondral cell types are derived. Chondrogenic hypertrophy was also enhanced specifically in high pO2 regions. Consequently, mineralised constructs with higher structural integrity, volume, and tailored dimensions are achieved. In contrast, a continuous osteogenic differentiation regime (os-os) has derived compact and dense constructs, whereas a continuous chondrogenic differentiation regime (ch-ch) has attenuated construct mineralisation and impaired development. In conclusion, a growth factor-free differentiation approach is achieved through interplay of pO2, medium pH, and systematic differentiation regimes. The controlled dynamic niches have recapitulated endochondral ossification and can potentially be exploited to derive larger bone constructs with near physiological properties. © 2019 John Wiley & Sons, Ltd.},
      author_keywords={bone development; murine embryonic stem cells; nodules; perfusion bioreactor; stem cell differentiation; tissue engineering},
      keywords={Bioconversion; Bioreactors; Bone; Cell engineering; Cytology; Oxygen; Sulfur compounds; Tissue engineering, Bone development; Chondrogenic; Controlled dynamics; Growth factor; Murine embryonic stem cells; Nodule; Oxygen tension; Perfusion bioreactor; Stem cell differentiation; Tissues engineerings, Stem cells, chondroitin 4 sulfate; growth factor; oxygen, animal cell; animal tissue; Article; bone development; bone malformation; bone mineralization; bone structure; bone volume; cell aggregation; cell density; cell differentiation; cellular distribution; chondrogenesis; controlled study; disease course; embryo; enchondral ossification; gene expression; histopathology; mouse; mouse embryonic stem cell; nonhuman; osteoclastogenesis; oxygen tension; pH; priority journal; signal transduction; tissue engineering; Young modulus; animal; bioreactor; bone development; cell shape; chemistry; culture medium; cytology; drug effect; gene expression regulation; metabolism; multicellular spheroid; perfusion; pharmacology; tissue scaffold, Animals; Bioreactors; Bone Development; Cell Aggregation; Cell Differentiation; Cell Shape; Culture Media; Elastic Modulus; Gene Expression Regulation; Hydrogen-Ion Concentration; Mice; Mouse Embryonic Stem Cells; Oxygen; Perfusion; Spheroids, Cellular; Tissue Scaffolds},
      correspondence_address1={Lee, P.S.; Institute for Materials Science, Germany; email: poh_soo.lee2@tu-dresden.de},
      publisher={John Wiley and Sons Ltd},
      issn={19326254},
      pubmed_id={31250556},
      language={English},
      abbrev_source_title={J. Tissue Eng. Regen. Med.},
      document_type={Article},
      source={Scopus},
      }

  • Direct Assembly and Metal-Ion Binding Properties of Oxytocin Monolayer on Gold Surfaces
    • E. Mervinetsky, I. Alshanski, J. Buchwald, A. Dianat, I. Lončarić, P. Lazić, Ž. Crljen, R. Gutierrez, G. Cuniberti, M. Hurevich, S. Yitzchaik
    • Langmuir 35, 11114-11122 (2019)
    • DOI   Abstract  

      Peptides are very common recognition entities that are usually attached to surfaces using multistep processes. These processes require modification of the native peptides and of the substrates. Using functional groups in native peptides for their assembly on surfaces without affecting their biological activity can facilitate the preparation of biosensors. Herein, we present a simple single-step formation of native oxytocin monolayer on gold surface. These surfaces were characterized by atomic force spectroscopy, spectroscopic ellipsometry, and X-ray photoelectron spectroscopy. We took advantage of the native disulfide bridge of the oxytocin for anchoring the peptide to the Au surface, while preserving the metal-ion binding properties. Self-assembled oxytocin monolayer was used by electrochemical impedance spectroscopy for metal-ion sensing leading to subnanomolar sensitivities for zinc or copper ions. © 2019 American Chemical Society.

      @ARTICLE{Mervinetsky201911114,
      author={Mervinetsky, E. and Alshanski, I. and Buchwald, J. and Dianat, A. and Lončarić, I. and Lazić, P. and Crljen, Ž. and Gutierrez, R. and Cuniberti, G. and Hurevich, M. and Yitzchaik, S.},
      title={Direct Assembly and Metal-Ion Binding Properties of Oxytocin Monolayer on Gold Surfaces},
      journal={Langmuir},
      year={2019},
      volume={35},
      number={34},
      pages={11114-11122},
      doi={10.1021/acs.langmuir.9b01830},
      note={cited By 6},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070943009&doi=10.1021%2facs.langmuir.9b01830&partnerID=40&md5=131acac3dcdb6d6dc46b5163d2f98972},
      affiliation={Institute of Chemistry, Hebrew University of Jerusalem, E. Safra Campus, Jerusalem, 91904, Israel; Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, E. Safra Campus, Jerusalem, 91904, Israel; Institute for Materials Science, Max Bergmann Center of Biomaterials, Hallwachsstraße 3, Dresden, 01062, Germany; Ruder Bošković Institute, Bijenička cesta 54, Zagreb, 10000, Croatia; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={Peptides are very common recognition entities that are usually attached to surfaces using multistep processes. These processes require modification of the native peptides and of the substrates. Using functional groups in native peptides for their assembly on surfaces without affecting their biological activity can facilitate the preparation of biosensors. Herein, we present a simple single-step formation of native oxytocin monolayer on gold surface. These surfaces were characterized by atomic force spectroscopy, spectroscopic ellipsometry, and X-ray photoelectron spectroscopy. We took advantage of the native disulfide bridge of the oxytocin for anchoring the peptide to the Au surface, while preserving the metal-ion binding properties. Self-assembled oxytocin monolayer was used by electrochemical impedance spectroscopy for metal-ion sensing leading to subnanomolar sensitivities for zinc or copper ions. © 2019 American Chemical Society.},
      keywords={Binding energy; Bioactivity; Covalent bonds; Electrochemical impedance spectroscopy; Gold; Gold metallurgy; Metal ions; Peptides; Spectroscopic ellipsometry; Sulfur compounds; X ray photoelectron spectroscopy, Atomic force spectroscopy; Common recognition; Disulfide bridge; Gold surfaces; Metal ion sensing; Metal-ion binding properties; Multistep process; Single-step, Monolayers},
      correspondence_address1={Crljen, Ž.; Ruder Bošković Institute, Bijenička cesta 54, Croatia; email: Zeljko.Crljen@irb.hr},
      publisher={American Chemical Society},
      issn={07437463},
      coden={LANGD},
      pubmed_id={31361147},
      language={English},
      abbrev_source_title={Langmuir},
      document_type={Article},
      source={Scopus},
      }

  • Influence of Mesityl and Thiophene Peripheral Substituents on Surface Attachment, Redox Chemistry, and ORR Activity of Molecular Iron Porphyrin Catalysts on Electrodes
    • R. Götz, K. H. Ly, P. Wrzolek, A. Dianat, A. Croy, G. Cuniberti, P. Hildebrandt, M. Schwalbe, I. M. Weidinger
    • Inorganic Chemistry 58, 10637-10647 (2019)
    • DOI   Abstract  

      Two iron porphyrin complexes with either mesityl (FeTMP) or thiophene (FeT3ThP) peripheral substituents were attached to basal pyrolytic graphite and Ag electrodes via different immobilization methods. By combining cyclic voltammetry and in-operando surface-enhanced Raman spectroscopy along with MD simulations and DFT calculations, their respective surface attachment, redox chemistry and activity toward electrocatalytic oxygen reduction was investigated. For both porphyrin complexes, it could be shown that catalytic activity is restricted to the first (few) molecular layer(s), although electrodes covered with thiophene-substituted complexes showed a better capability to consume the oxygen at a given overpotential even in thicker films. The spectroscopic data and simulations suggest that both porphyrin complexes attach to a Ag electrode surface in a way that maximum planarity and minimum distance between the catalytic iron site and the electrode is achieved. However, due to the distinctive design of the FeT3ThP complex, the thiophene rings are capable of occupying a conformation, via rotation around the bonding axis to the porphyrin, in which all four sulfur atoms can coordinate to the Ag surface. This effect creates a dense and planar surface coverage of the porphyrin on the electrode facilitating a fast (multi) electron transfer via several covalent Ag-S bonds. In contrast, bulky mesityl groups as peripheral substituents, which have been initially introduced to prevent aggregation and improve catalytic behavior in solution, exert a negative effect on the overall electrocatalytic performance in the immobilized state as a less dense coverage and less stable interactions with the surface are formed. Our results underline the importance of rationally designed heterogenized molecular catalysts to achieve optimal turnover, which not only strictly applies to the here discussed oxygen reduction reaction but eventually holds also true for other energy conversion reactions such as carbon dioxide reduction. © 2019 American Chemical Society.

      @ARTICLE{Götz201910637,
      author={Götz, R. and Ly, K.H. and Wrzolek, P. and Dianat, A. and Croy, A. and Cuniberti, G. and Hildebrandt, P. and Schwalbe, M. and Weidinger, I.M.},
      title={Influence of Mesityl and Thiophene Peripheral Substituents on Surface Attachment, Redox Chemistry, and ORR Activity of Molecular Iron Porphyrin Catalysts on Electrodes},
      journal={Inorganic Chemistry},
      year={2019},
      volume={58},
      number={16},
      pages={10637-10647},
      doi={10.1021/acs.inorgchem.9b00043},
      note={cited By 8},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070966873&doi=10.1021%2facs.inorgchem.9b00043&partnerID=40&md5=02deb939140c634b0a70c5a22ecc3257},
      affiliation={Faculty of Chemistry and Food Chemistry, Dresden University of Technology, Dresden, 01062, Germany; Institute of Chemistry, Humboldt-Universität zu Berlin, Berlin, 12489, Germany; Institute for Materials Science, Max Bergmann Center of Biomaterials, Dresden University of Technology, Dresden, 01062, Germany; Center for Advancing Electronics, Dresden Center for Computational Materials Science, Dresden University of Technology, Dresden, 01062, Germany; Institute of Chemistry, Technische Universität Berlin, Berlin, 10623, Germany},
      abstract={Two iron porphyrin complexes with either mesityl (FeTMP) or thiophene (FeT3ThP) peripheral substituents were attached to basal pyrolytic graphite and Ag electrodes via different immobilization methods. By combining cyclic voltammetry and in-operando surface-enhanced Raman spectroscopy along with MD simulations and DFT calculations, their respective surface attachment, redox chemistry and activity toward electrocatalytic oxygen reduction was investigated. For both porphyrin complexes, it could be shown that catalytic activity is restricted to the first (few) molecular layer(s), although electrodes covered with thiophene-substituted complexes showed a better capability to consume the oxygen at a given overpotential even in thicker films. The spectroscopic data and simulations suggest that both porphyrin complexes attach to a Ag electrode surface in a way that maximum planarity and minimum distance between the catalytic iron site and the electrode is achieved. However, due to the distinctive design of the FeT3ThP complex, the thiophene rings are capable of occupying a conformation, via rotation around the bonding axis to the porphyrin, in which all four sulfur atoms can coordinate to the Ag surface. This effect creates a dense and planar surface coverage of the porphyrin on the electrode facilitating a fast (multi) electron transfer via several covalent Ag-S bonds. In contrast, bulky mesityl groups as peripheral substituents, which have been initially introduced to prevent aggregation and improve catalytic behavior in solution, exert a negative effect on the overall electrocatalytic performance in the immobilized state as a less dense coverage and less stable interactions with the surface are formed. Our results underline the importance of rationally designed heterogenized molecular catalysts to achieve optimal turnover, which not only strictly applies to the here discussed oxygen reduction reaction but eventually holds also true for other energy conversion reactions such as carbon dioxide reduction. © 2019 American Chemical Society.},
      correspondence_address1={Schwalbe, M.; Institute of Chemistry, Germany; email: matthias.schwalbe@hu-berlin.de},
      publisher={American Chemical Society},
      issn={00201669},
      coden={INOCA},
      pubmed_id={31385516},
      language={English},
      abbrev_source_title={Inorg. Chem.},
      document_type={Article},
      source={Scopus},
      }

  • Straintronics in graphene: Extra large electronic band gap induced by tensile and shear strains
    • I. Y. Sahalianov, T. M. Radchenko, V. A. Tatarenko, G. Cuniberti, Y. I. Prylutskyy
    • Journal of Applied Physics 126, 054302 (2019)
    • DOI   Abstract  

      The possibility of inducing a sizeable energy gap in the electronic structure of a graphene layer is still one of the biggest and most debated challenges in graphene electronics. Despite promising theoretical results, some experimental studies report the absence of a bandgap even in highly mechanically strained graphene. In this paper, we address the main reasons for these discrepancies and study the influence of uniaxial tensile and shear strains as well as their combinations on the eventual bandgap opening in monolayer graphene. Deformation-dependent bandgap diagrams are constructed over a wide range of the strain tensor parameters of up to 26%, which is close to predicted graphene breaking point. The use of a combination of shear strain and uniaxial tensile deformations is found to be the easiest way for bandgap opening and tuning. The results of our numerical calculations demonstrate that shear strains can induce a bandgap of up to 4 eV at the largest elastic deformations, while a combination of shear and uniaxial strains can provide an energy gap of up to 6 eV that is substantially higher than for some materials (including silicon) typically used in nanoelectronic devices. The numerically obtained findings are carefully contrasted with other results available in the literature. © 2019 Author(s).

      @ARTICLE{Sahalianov2019,
      author={Sahalianov, I.Y. and Radchenko, T.M. and Tatarenko, V.A. and Cuniberti, G. and Prylutskyy, Y.I.},
      title={Straintronics in graphene: Extra large electronic band gap induced by tensile and shear strains},
      journal={Journal of Applied Physics},
      year={2019},
      volume={126},
      number={5},
      doi={10.1063/1.5095600},
      art_number={054302},
      note={cited By 37},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85073890432&doi=10.1063%2f1.5095600&partnerID=40&md5=ecdafab45cf2f51ccb31e709304eafee},
      affiliation={Linköping University, Norrköping, 60174, Sweden; G. V. Kurdyumov Institute for Metal Physics of the NAS of Ukraine, Kyiv, 03142, Ukraine; Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Taras Shevchenko National University of Kyiv, Kyiv, 03127, Ukraine},
      abstract={The possibility of inducing a sizeable energy gap in the electronic structure of a graphene layer is still one of the biggest and most debated challenges in graphene electronics. Despite promising theoretical results, some experimental studies report the absence of a bandgap even in highly mechanically strained graphene. In this paper, we address the main reasons for these discrepancies and study the influence of uniaxial tensile and shear strains as well as their combinations on the eventual bandgap opening in monolayer graphene. Deformation-dependent bandgap diagrams are constructed over a wide range of the strain tensor parameters of up to 26%, which is close to predicted graphene breaking point. The use of a combination of shear strain and uniaxial tensile deformations is found to be the easiest way for bandgap opening and tuning. The results of our numerical calculations demonstrate that shear strains can induce a bandgap of up to 4 eV at the largest elastic deformations, while a combination of shear and uniaxial strains can provide an energy gap of up to 6 eV that is substantially higher than for some materials (including silicon) typically used in nanoelectronic devices. The numerically obtained findings are carefully contrasted with other results available in the literature. © 2019 Author(s).},
      keywords={Deformation; Electronic structure; Energy gap; Shear strain, Band-gap diagram; Bandgap openings; Electronic band gaps; Nanoelectronic devices; Numerical calculation; Strained graphene; Uni-axial strains; Uniaxial tensile deformation, Graphene},
      publisher={American Institute of Physics Inc.},
      issn={00218979},
      coden={JAPIA},
      language={English},
      abbrev_source_title={J Appl Phys},
      document_type={Article},
      source={Scopus},
      }

  • Exploring the write-in process in molecular quantum cellular automata: A combined modelingand first-principle approach
    • A. Santana-Bonilla, L. Medrano Sandonas, R. Gutierrez, G. Cuniberti
    • Journal of Physics Condensed Matter 31, 405502 (2019)
    • DOI   Abstract  

      The molecular quantum cellular automata paradigm (m-QCA) offers a promising alternative framework to current CMOS implementations. A crucial aspect for implementing this technology concerns the construction of a device which effectively controls intramolecular charge-transfer processes. Tentative experimental implementations have been developed in which a voltage drop is created generating the forces that drive a molecule into a logic state. However, important factors such as the electric field profile, its possible time-dependency and the influence of temperature in the overall success of charge-transfer are relevant issues to be considered in the design of a reliable device. In this work, we theoretically study the role played by these processes in the overall intramolecular charge-transfer process. We have used a Landau-Zener (LZ) model, where different time-dependent electric field profiles have been simulated. The results have been further corroborated employing density functional tight-binding method. The role played by the nuclear motions in the electron-transfer process has been investigated beyond the Born-Oppenheimer approximation by computing the effect of the external electric field in the behavior of the potential energy surface. Hence, we demonstrate that the intramolecular charge-transfer process is a direct consequence of the coherent LZ nonadiabatic tunneling and the hybridization of the diabatic vibronic states which effectively reduces the trapping of the itinerant electron at the donor group. © 2019 IOP Publishing Ltd.

      @ARTICLE{Santana-Bonilla2019,
      author={Santana-Bonilla, A. and Medrano Sandonas, L. and Gutierrez, R. and Cuniberti, G.},
      title={Exploring the write-in process in molecular quantum cellular automata: A combined modelingand first-principle approach},
      journal={Journal of Physics Condensed Matter},
      year={2019},
      volume={31},
      number={40},
      doi={10.1088/1361-648X/ab29c1},
      art_number={405502},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071067573&doi=10.1088%2f1361-648X%2fab29c1&partnerID=40&md5=d9f6650c418b2422ac59cd1b02bd20be},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, Dresden University of Technology, Dresden, 01062, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany; Center for Advancing Electronics Dresden, Dresden University of Technology, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Dresden University of Technology, Dresden, 01062, Germany},
      abstract={The molecular quantum cellular automata paradigm (m-QCA) offers a promising alternative framework to current CMOS implementations. A crucial aspect for implementing this technology concerns the construction of a device which effectively controls intramolecular charge-transfer processes. Tentative experimental implementations have been developed in which a voltage drop is created generating the forces that drive a molecule into a logic state. However, important factors such as the electric field profile, its possible time-dependency and the influence of temperature in the overall success of charge-transfer are relevant issues to be considered in the design of a reliable device. In this work, we theoretically study the role played by these processes in the overall intramolecular charge-transfer process. We have used a Landau-Zener (LZ) model, where different time-dependent electric field profiles have been simulated. The results have been further corroborated employing density functional tight-binding method. The role played by the nuclear motions in the electron-transfer process has been investigated beyond the Born-Oppenheimer approximation by computing the effect of the external electric field in the behavior of the potential energy surface. Hence, we demonstrate that the intramolecular charge-transfer process is a direct consequence of the coherent LZ nonadiabatic tunneling and the hybridization of the diabatic vibronic states which effectively reduces the trapping of the itinerant electron at the donor group. © 2019 IOP Publishing Ltd.},
      author_keywords={charge transfer; density functional tight binding (DFTB); non-adiabatic coupling; quantum cellular automata},
      keywords={Binding energy; Cellular automata; Electric fields; Electron transport properties; Potential energy; Quantum chemistry, Born-Oppenheimer approximation; Density functional tight binding method; Density functional tight bindings; Electron transfer process; Intra-molecular charge transfer; Non-adiabatic coupling; Quantum Cellular automata; Time-dependent electric field, Charge transfer},
      publisher={Institute of Physics Publishing},
      issn={09538984},
      coden={JCOME},
      pubmed_id={31195387},
      language={English},
      abbrev_source_title={J Phys Condens Matter},
      document_type={Article},
      source={Scopus},
      }

  • A finite element approach for vector- and tensor-valued surface PDEs
    • M. Nestler, I. Nitschke, A. Voigt
    • Journal of Computational Physics 389, 48-61 (2019)
    • DOI   Abstract  

      We derive a Cartesian componentwise description of the covariant derivative of tangential tensor fields of any degree on Riemannian manifolds. This allows to reformulate any vector- and tensor-valued surface PDE in a form suitable to be solved by established tools for scalar-valued surface PDEs. We consider piecewise linear Lagrange surface finite elements on triangulated surfaces and validate the approach by a vector- and a tensor-valued surface Helmholtz problem on an ellipsoid. We experimentally show optimal (linear) order of convergence for these problems. The full functionality is demonstrated by solving a surface Landau-de Gennes problem on the Stanford bunny. All tools required to apply this approach to other vector- and tensor-valued surface PDEs are provided. © 2019 Elsevier Inc.

      @ARTICLE{Nestler201948,
      author={Nestler, M. and Nitschke, I. and Voigt, A.},
      title={A finite element approach for vector- and tensor-valued surface PDEs},
      journal={Journal of Computational Physics},
      year={2019},
      volume={389},
      pages={48-61},
      doi={10.1016/j.jcp.2019.03.006},
      note={cited By 17},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063877402&doi=10.1016%2fj.jcp.2019.03.006&partnerID=40&md5=8bede36a144444ecd1a409499e13050f},
      affiliation={Institut für Wissenschaftliches Rechnen, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Center for Systems Biology Dresden (CSBD), Pfotenhauerstr. 108, Dresden, 01307, Germany},
      abstract={We derive a Cartesian componentwise description of the covariant derivative of tangential tensor fields of any degree on Riemannian manifolds. This allows to reformulate any vector- and tensor-valued surface PDE in a form suitable to be solved by established tools for scalar-valued surface PDEs. We consider piecewise linear Lagrange surface finite elements on triangulated surfaces and validate the approach by a vector- and a tensor-valued surface Helmholtz problem on an ellipsoid. We experimentally show optimal (linear) order of convergence for these problems. The full functionality is demonstrated by solving a surface Landau-de Gennes problem on the Stanford bunny. All tools required to apply this approach to other vector- and tensor-valued surface PDEs are provided. © 2019 Elsevier Inc.},
      author_keywords={Finite element method; Liquid crystals; Surface PDEs; Tensor fields},
      keywords={Liquid crystals; Piecewise linear techniques; Tensors; Vectors, Covariant derivatives; Finite-element approach; Helmholtz problems; Order of convergence; Riemannian manifold; Surface finite elements; Tensor fields; Triangulated surfaces, Finite element method},
      correspondence_address1={Nestler, M.; Institut für Wissenschaftliches Rechnen, Germany; email: michael.nestler@tu-dresden.de},
      publisher={Academic Press Inc.},
      issn={00219991},
      coden={JCTPA},
      language={English},
      abbrev_source_title={J. Comput. Phys.},
      document_type={Article},
      source={Scopus},
      }

  • Competition Between Kinetics and Thermodynamics During the Growth of Faceted Crystal by Phase Field Modeling
    • M. Albani, R. Bergamaschini, M. Salvalaglio, A. Voigt, L. Miglio, F. Montalenti
    • Physica Status Solidi (B) Basic Research 256, 1800518 (2019)
    • DOI   Abstract  

      The faceting of a growing crystal is theoretically investigated by a continuum model including the incorporation kinetics of adatoms. This allows us for predictions beyond a simple Wulff analysis which typically refers to faceted morphologies in terms of the equilibrium crystal shape for crystals with an anisotropic surface-energy, or to steady-state kinetic shape when the crystals grow with orientation-dependent velocities. A phase-field approach is implemented in order to account simultaneously for these contributions in two- and three dimensions reproducing realistic kinetic pathways for the morphological evolution of crystal surfaces during growth. After a systematic characterization of the faceting determined by orientation-dependent incorporation times, several different crystal morphologies are found by tuning the relative weights of thermodynamic and kinetic driving forces. Applications to realistic systems are finally reported showing the versatility of the proposed approach and demonstrating the key role played by the incorporation dynamics in out-of-equilibrium growth processes. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

      @ARTICLE{Albani2019,
      author={Albani, M. and Bergamaschini, R. and Salvalaglio, M. and Voigt, A. and Miglio, L. and Montalenti, F.},
      title={Competition Between Kinetics and Thermodynamics During the Growth of Faceted Crystal by Phase Field Modeling},
      journal={Physica Status Solidi (B) Basic Research},
      year={2019},
      volume={256},
      number={7},
      doi={10.1002/pssb.201800518},
      art_number={1800518},
      note={cited By 18},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059855966&doi=10.1002%2fpssb.201800518&partnerID=40&md5=1e9da1e13e0c4adcc62d9f817d0e2dd9},
      affiliation={L-NESS and Department of Materials Science, Università di Milano − Bicocca, Milano, 20125, Italy; Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={The faceting of a growing crystal is theoretically investigated by a continuum model including the incorporation kinetics of adatoms. This allows us for predictions beyond a simple Wulff analysis which typically refers to faceted morphologies in terms of the equilibrium crystal shape for crystals with an anisotropic surface-energy, or to steady-state kinetic shape when the crystals grow with orientation-dependent velocities. A phase-field approach is implemented in order to account simultaneously for these contributions in two- and three dimensions reproducing realistic kinetic pathways for the morphological evolution of crystal surfaces during growth. After a systematic characterization of the faceting determined by orientation-dependent incorporation times, several different crystal morphologies are found by tuning the relative weights of thermodynamic and kinetic driving forces. Applications to realistic systems are finally reported showing the versatility of the proposed approach and demonstrating the key role played by the incorporation dynamics in out-of-equilibrium growth processes. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim},
      author_keywords={crystal faceting; incorporation time; kinetics; phase-field; surface diffusion},
      keywords={Continuum mechanics; Crystals; Enzyme kinetics; Growth kinetics; Kinetics; Surface diffusion; Thermodynamics, Anisotropic surface energy; Crystal faceting; Equilibrium crystal shapes; incorporation time; Kinetics and thermodynamics; Morphological evolution; Phase fields; Phase-field approaches, Crystal orientation},
      correspondence_address1={Albani, M.; L-NESS and Department of Materials Science, Italy; email: marco.albani@unimib.it},
      publisher={Wiley-VCH Verlag},
      issn={03701972},
      language={English},
      abbrev_source_title={Phys. Status Solidi B Basic Res.},
      document_type={Article},
      source={Scopus},
      }

  • Electron transport through NiSi2-Si contacts and their role in reconfigurable field-effect transistors
    • F. Fuchs, S. Gemming, J. Schuster
    • Journal of Physics Condensed Matter 31, 355002 (2019)
    • DOI   Abstract  

      A model is presented which describes reconfigurable field-effect transistors (RFETs) with metal contacts, whose switching is controlled by manipulating the Schottky barriers at the contacts. The proposed modeling approach is able to bridge the gap between quantum effects on the atomic scale and the transistor switching. We apply the model to transistors with a silicon channel and NiSi2 contacts. All relevant crystal orientations are compared, focusing on the differences between electron and hole current, which can be as large as four orders of magnitude. Best symmetry is found for the orientation, which makes this orientation most advantageous for RFETs. The observed differences are analyzed in terms of the Schottky barrier height at the interface. Our study indicates that the precise orientation of the interface relative to a given transport direction, perpendicular or tilted, is an important technology parameter, which has been underestimated during the previous development of RFETs. Most of the conclusions regarding the studied metal-semiconductor interface are also valid for other device architectures. © 2019 IOP Publishing Ltd.

      @ARTICLE{Fuchs2019,
      author={Fuchs, F. and Gemming, S. and Schuster, J.},
      title={Electron transport through NiSi2-Si contacts and their role in reconfigurable field-effect transistors},
      journal={Journal of Physics Condensed Matter},
      year={2019},
      volume={31},
      number={35},
      doi={10.1088/1361-648X/ab2310},
      art_number={355002},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85069889762&doi=10.1088%2f1361-648X%2fab2310&partnerID=40&md5=9cc716b6f4696fa39c91ab909e44a4ce},
      affiliation={Institute of Physics, Chemnitz University of Technology, Chemnitz, Germany; Center for Advancing Electronics Dresden, Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Dresden, Germany; Fraunhofer Institute for Electronic Nano Systems, Chemnitz, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, Germany; Center for Microtechnologies, Chemnitz University of Technology, Chemnitz, Germany},
      abstract={A model is presented which describes reconfigurable field-effect transistors (RFETs) with metal contacts, whose switching is controlled by manipulating the Schottky barriers at the contacts. The proposed modeling approach is able to bridge the gap between quantum effects on the atomic scale and the transistor switching. We apply the model to transistors with a silicon channel and NiSi2 contacts. All relevant crystal orientations are compared, focusing on the differences between electron and hole current, which can be as large as four orders of magnitude. Best symmetry is found for the orientation, which makes this orientation most advantageous for RFETs. The observed differences are analyzed in terms of the Schottky barrier height at the interface. Our study indicates that the precise orientation of the interface relative to a given transport direction, perpendicular or tilted, is an important technology parameter, which has been underestimated during the previous development of RFETs. Most of the conclusions regarding the studied metal-semiconductor interface are also valid for other device architectures. © 2019 IOP Publishing Ltd.},
      author_keywords={density functional theory; electron transport; metal-semiconductor interface; nickel silicide; Schottky barrier; silicon},
      keywords={Crystal orientation; Density functional theory; Electron transport properties; Nickel compounds; Quantum theory; Schottky barrier diodes; Silicides; Silicon, Device architectures; Electron transport; Metal semiconductor interface; Nickel silicide; Schottky barrier heights; Schottky barriers; Technology parameters; Transistor switching, Field effect transistors},
      publisher={Institute of Physics Publishing},
      issn={09538984},
      coden={JCOME},
      pubmed_id={31108482},
      language={English},
      abbrev_source_title={J Phys Condens Matter},
      document_type={Article},
      source={Scopus},
      }

  • Combined molecular dynamics and phase-field modelling of crack propagation in defective graphene
    • A. C. Hansen-Dörr, L. Wilkens, A. Croy, A. Dianat, G. Cuniberti, M. Kästner
    • Computational Materials Science 163, 117-126 (2019)
    • DOI   Abstract  

      In this work, a combined modelling approach for crack propagation in defective graphene is presented. Molecular dynamics (MD) simulations are used to obtain material parameters (YOUNG’s modulus and Poisson ratio) and to determine the energy contributions during the crack evolution. The elastic properties are then applied in phase-field continuum simulations which are based on the Griffith energy criterion for fracture. In particular, the influence of point defects on elastic properties and the fracture toughness are investigated. For the latter, we obtain values consistent with recent experimental findings. Further, we discuss alternative definitions of an effective fracture toughness, which accounts for the conditions of crack propagation and establishes a link between dynamic, discrete and continuous, quasi-static fracture processes on MD level and continuum level, respectively. It is demonstrated that the combination of MD and phase-field simulations is a well-founded approach to identify defect-dependent material parameters. © 2019

      @ARTICLE{Hansen-Dörr2019117,
      author={Hansen-Dörr, A.C. and Wilkens, L. and Croy, A. and Dianat, A. and Cuniberti, G. and Kästner, M.},
      title={Combined molecular dynamics and phase-field modelling of crack propagation in defective graphene},
      journal={Computational Materials Science},
      year={2019},
      volume={163},
      pages={117-126},
      doi={10.1016/j.commatsci.2019.03.028},
      note={cited By 14},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063272269&doi=10.1016%2fj.commatsci.2019.03.028&partnerID=40&md5=0fb6c712efa599642b3e4c8111dbc41a},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, Germany; Institute of Materials Science, TU Dresden, Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, Germany},
      abstract={In this work, a combined modelling approach for crack propagation in defective graphene is presented. Molecular dynamics (MD) simulations are used to obtain material parameters (YOUNG's modulus and Poisson ratio) and to determine the energy contributions during the crack evolution. The elastic properties are then applied in phase-field continuum simulations which are based on the Griffith energy criterion for fracture. In particular, the influence of point defects on elastic properties and the fracture toughness are investigated. For the latter, we obtain values consistent with recent experimental findings. Further, we discuss alternative definitions of an effective fracture toughness, which accounts for the conditions of crack propagation and establishes a link between dynamic, discrete and continuous, quasi-static fracture processes on MD level and continuum level, respectively. It is demonstrated that the combination of MD and phase-field simulations is a well-founded approach to identify defect-dependent material parameters. © 2019},
      author_keywords={Combined approach; Fracture of defective graphene; Molecular dynamics; Phase-field modelling},
      keywords={Crack propagation; Elastic moduli; Elasticity; Fracture toughness; Graphene; Molecular dynamics; Point defects, Combined approach; Continuum simulations; Effective fracture toughness; Energy contribution; Molecular dynamics simulations; Phase field modelling; Phase-field simulation; Quasistatic fracture, Cracks},
      correspondence_address1={Cuniberti, G.; Institute of Materials Science, Germany; email: gianaurelio.cuniberti@tu-dresden.de},
      publisher={Elsevier B.V.},
      issn={09270256},
      coden={CMMSE},
      language={English},
      abbrev_source_title={Comput Mater Sci},
      document_type={Article},
      source={Scopus},
      }

  • Influence of lattice termination on the edge states of the quantum spin Hall insulator monolayer 1T′-WTe2
    • A. Lau, R. Ray, D. Varjas, A. R. Akhmerov
    • Physical Review Materials 3, 054206 (2019)
    • DOI   Abstract  

      We study the influence of sample termination on the electronic properties of the novel quantum spin Hall insulator monolayer 1T′-WTe2. For this purpose, we construct an accurate, minimal four-orbital tight-binding model with spin-orbit coupling by employing a combination of density-functional theory calculations, symmetry considerations, and fitting to experimental data. Based on this model, we compute energy bands and two-terminal conductance spectra for various ribbon geometries with different terminations, with and without a magnetic field. Because of the strong electron-hole asymmetry, we find that the edge Dirac point is buried in the bulk bands for most edge terminations. In the presence of a magnetic field, an in-gap edge Dirac point leads to exponential suppression of conductance as an edge Zeeman gap opens, whereas the conductance stays at the quantized value when the Dirac point is buried in the bulk bands. Finally, we find that disorder in the edge termination drastically changes this picture: the conductance of a sufficiently rough edge is uniformly suppressed for all energies in the bulk gap regardless of the orientation of the edge. © 2019 American Physical Society.

      @ARTICLE{Lau2019,
      author={Lau, A. and Ray, R. and Varjas, D. and Akhmerov, A.R.},
      title={Influence of lattice termination on the edge states of the quantum spin Hall insulator monolayer 1T′-WTe2},
      journal={Physical Review Materials},
      year={2019},
      volume={3},
      number={5},
      doi={10.1103/PhysRevMaterials.3.054206},
      art_number={054206},
      note={cited By 19},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066789765&doi=10.1103%2fPhysRevMaterials.3.054206&partnerID=40&md5=76433cb5e38ac2ec4b34f358a5fd9c9a},
      affiliation={Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 4056, Delft, 2600 GA, Netherlands; Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstr. 20, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; QuTech, Delft University of Technology, P.O. Box 4056, Delft, 2600 GA, Netherlands},
      abstract={We study the influence of sample termination on the electronic properties of the novel quantum spin Hall insulator monolayer 1T′-WTe2. For this purpose, we construct an accurate, minimal four-orbital tight-binding model with spin-orbit coupling by employing a combination of density-functional theory calculations, symmetry considerations, and fitting to experimental data. Based on this model, we compute energy bands and two-terminal conductance spectra for various ribbon geometries with different terminations, with and without a magnetic field. Because of the strong electron-hole asymmetry, we find that the edge Dirac point is buried in the bulk bands for most edge terminations. In the presence of a magnetic field, an in-gap edge Dirac point leads to exponential suppression of conductance as an edge Zeeman gap opens, whereas the conductance stays at the quantized value when the Dirac point is buried in the bulk bands. Finally, we find that disorder in the edge termination drastically changes this picture: the conductance of a sufficiently rough edge is uniformly suppressed for all energies in the bulk gap regardless of the orientation of the edge. © 2019 American Physical Society.},
      keywords={Electronic properties; Magnetic fields; Monolayers; Quantum theory, Edge termination; Electron-hole asymmetry; Quantized value; Quantum spin halls; Spin-orbit couplings; Symmetry consideration; Tight binding model; Two-terminal conductance, Density functional theory},
      publisher={American Physical Society},
      issn={24759953},
      language={English},
      abbrev_source_title={Physic. Rev. Mat.},
      document_type={Article},
      source={Scopus},
      }

  • Photocatalytic microporous membrane against the increasing problem of water emerging pollutants
    • P. M. Martins, J. M. Ribeiro, S. Teixeira, D. Y. Petrovykh, G. Cuniberti, L. Pereira, S. Lanceros-Méndez
    • Materials 12, 1649 (2019)
    • DOI   Abstract  

      Emerging pollutants are an essential class of recalcitrant contaminants that are not eliminated from water after conventional treatment. Here, a photocatalytic microporous membrane based on polyvinylidene difluoride-co-trifluoroethylene (PVDF-TrFE) with immobilised TiO2 nanoparticles, prepared by solvent casting, was tested against representative emerging pollutants. The structure and composition of these polymeric membranes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, porosimetry, and contact angle goniometry. The nanocomposites exhibited a porous structure with a uniform distribution of TiO2 nanoparticles. The addition of TiO2 did not change the structure of the polymeric matrix; however, it increased the wettability of the nanocomposite. The nanocomposites degraded 99% of methylene blue (MB), 95% of ciprofloxacin (CIP), and 48% of ibuprofen (IBP). The microporous nanocomposite exhibited no photocatalytic efficiency loss after four use cycles, corresponding to 20 h of UV irradiation. The reusability of this system confirms the promising nature of polymer nanocomposites as the basis for cost-effective and scalable treatments of emerging pollutants. © 2019 by the authors.

      @ARTICLE{Martins2019,
      author={Martins, P.M. and Ribeiro, J.M. and Teixeira, S. and Petrovykh, D.Y. and Cuniberti, G. and Pereira, L. and Lanceros-Méndez, S.},
      title={Photocatalytic microporous membrane against the increasing problem of water emerging pollutants},
      journal={Materials},
      year={2019},
      volume={12},
      number={10},
      doi={10.3390/ma12101649},
      art_number={1649},
      note={cited By 21},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85066834498&doi=10.3390%2fma12101649&partnerID=40&md5=9f5654c0e0a013b72fc16133cf5984f6},
      affiliation={Centre of Physics, University of Minho, Braga, 4710-057, Portugal; Department of Biological Engineering, University of Minho, Braga, 4710-057, Portugal; Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Braga, 4710-057, Portugal; Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, Braga, 4715-330, Portugal; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, Leioa, 48940, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain},
      abstract={Emerging pollutants are an essential class of recalcitrant contaminants that are not eliminated from water after conventional treatment. Here, a photocatalytic microporous membrane based on polyvinylidene difluoride-co-trifluoroethylene (PVDF-TrFE) with immobilised TiO2 nanoparticles, prepared by solvent casting, was tested against representative emerging pollutants. The structure and composition of these polymeric membranes were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, porosimetry, and contact angle goniometry. The nanocomposites exhibited a porous structure with a uniform distribution of TiO2 nanoparticles. The addition of TiO2 did not change the structure of the polymeric matrix; however, it increased the wettability of the nanocomposite. The nanocomposites degraded 99% of methylene blue (MB), 95% of ciprofloxacin (CIP), and 48% of ibuprofen (IBP). The microporous nanocomposite exhibited no photocatalytic efficiency loss after four use cycles, corresponding to 20 h of UV irradiation. The reusability of this system confirms the promising nature of polymer nanocomposites as the basis for cost-effective and scalable treatments of emerging pollutants. © 2019 by the authors.},
      author_keywords={Immobilization; Pharmaceuticals; Photocatalysis; PVDF-TrFE; Titanium dioxide},
      keywords={Aromatic compounds; Contact angle; Cost effectiveness; Drug products; Energy dispersive spectroscopy; Fourier transform infrared spectroscopy; Irradiation; Microporosity; Nanocomposites; Nanoparticles; Photocatalysis; Polymer matrix composites; Radioactive waste vitrification; Reusability; Scanning electron microscopy; Titanium castings; Titanium dioxide; Water pollution; Water treatment, Contact angle goniometry; Conventional treatments; Energy dispersive X ray spectroscopy; Micro porous membranes; Photocatalytic efficiency; Polymer nanocomposite; Polyvinylidene difluoride; PVDF-TrFE, TiO2 nanoparticles},
      correspondence_address1={Martins, P.M.; Centre of Physics, Portugal; email: pamartins@fisica.uminho.pt},
      publisher={MDPI AG},
      issn={19961944},
      language={English},
      abbrev_source_title={Mater.},
      document_type={Article},
      source={Scopus},
      }

  • Topological and geometrical quantities in active cellular structures
    • D. Wenzel, S. Praetorius, A. Voigt
    • Journal of Chemical Physics 150, 164108 (2019)
    • DOI   Abstract  

      Topological and geometrical properties and the associated topological defects find a rapidly growing interest in studying the interplay between mechanics and the collective behavior of cells on the tissue level. We here test if well studied equilibrium laws for polydisperse passive systems such as Lewis’ and Aboav-Weaire’s law are applicable also for active cellular structures. Large scale simulations, which are based on a multiphase field active polar gel model, indicate that these active cellular structures follow these laws. If the system is in a state of collective motion, quantitative agreement with typical values for passive systems is also observed. If this state has not developed, quantitative differences can be found. We further compare the model with discrete modeling approaches for cellular structures and show that essential properties, such as T1 transitions and rosettes, are naturally fulfilled. © 2019 Author(s).

      @ARTICLE{Wenzel2019,
      author={Wenzel, D. and Praetorius, S. and Voigt, A.},
      title={Topological and geometrical quantities in active cellular structures},
      journal={Journal of Chemical Physics},
      year={2019},
      volume={150},
      number={16},
      doi={10.1063/1.5085766},
      art_number={164108},
      note={cited By 11},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064910704&doi=10.1063%2f1.5085766&partnerID=40&md5=e66750f70a9b486a9303e8663a89538e},
      affiliation={Institute of Scientific Computing, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Center for Systems Biology Dresden (CSBD), Pfotenhauerstr. 108, Dresden, 01307, Germany},
      abstract={Topological and geometrical properties and the associated topological defects find a rapidly growing interest in studying the interplay between mechanics and the collective behavior of cells on the tissue level. We here test if well studied equilibrium laws for polydisperse passive systems such as Lewis' and Aboav-Weaire's law are applicable also for active cellular structures. Large scale simulations, which are based on a multiphase field active polar gel model, indicate that these active cellular structures follow these laws. If the system is in a state of collective motion, quantitative agreement with typical values for passive systems is also observed. If this state has not developed, quantitative differences can be found. We further compare the model with discrete modeling approaches for cellular structures and show that essential properties, such as T1 transitions and rosettes, are naturally fulfilled. © 2019 Author(s).},
      keywords={Topology, Cellular structure; Collective behavior; Collective motions; Geometrical property; Geometrical quantities; Large scale simulations; Quantitative agreement; Topological defect, Cellular automata, biological model; cells; cytology, Cells; Models, Biological},
      publisher={American Institute of Physics Inc.},
      issn={00219606},
      coden={JCPSA},
      pubmed_id={31042877},
      language={English},
      abbrev_source_title={J Chem Phys},
      document_type={Article},
      source={Scopus},
      }

  • Green function, quasi-classical Langevin and Kubo-Greenwood methods in quantum thermal transport
    • H. Sevinçli, S. Roche, G. Cuniberti, M. Brandbyge, R. Gutierrez, L. M. Sandonas
    • Journal of Physics Condensed Matter 31, 273003 (2019)
    • DOI   Abstract  

      With the advances in fabrication of materials with feature sizes at the order of nanometers, it has been possible to alter their thermal transport properties dramatically. Miniaturization of device size increases the power density in general, hence faster electronics require better thermal transport, whereas better thermoelectric applications require the opposite. Such diverse needs bring new challenges for material design. Shrinkage of length scales has also changed the experimental and theoretical methods to study thermal transport. Unsurprisingly, novel approaches have emerged to control phonon flow. Besides, ever increasing computational power is another driving force for developing new computational methods. In this review, we discuss three methods developed for computing vibrational thermal transport properties of nano-structured systems, namely Green function, quasi-classical Langevin, and Kubo-Green methods. The Green function methods are explained using both nonequilibrium expressions and the Landauer-type formula. The partitioning scheme, decimation techniques and surface Green functions are reviewed, and a simple model for reservoir Green functions is shown. The expressions for the Kubo-Greenwood method are derived, and Lanczos tridiagonalization, continued fraction and Chebyshev polynomial expansion methods are discussed. Additionally, the quasi-classical Langevin approach, which is useful for incorporating phonon-phonon and other scatterings is summarized. © 2019 IOP Publishing Ltd.

      @ARTICLE{Sevinçli2019,
      author={Sevinçli, H. and Roche, S. and Cuniberti, G. and Brandbyge, M. and Gutierrez, R. and Sandonas, L.M.},
      title={Green function, quasi-classical Langevin and Kubo-Greenwood methods in quantum thermal transport},
      journal={Journal of Physics Condensed Matter},
      year={2019},
      volume={31},
      number={27},
      doi={10.1088/1361-648X/ab119a},
      art_number={273003},
      note={cited By 13},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065809227&doi=10.1088%2f1361-648X%2fab119a&partnerID=40&md5=7a3e495715e59d22fc7882bd2e606669},
      affiliation={Department of Materials Science and Engineering, Izmir Institute of Technology, Urla, Izmir, 35430, Turkey; Catalan Institute of Nanoscience and Nanotechnology (ICN2), Campus UAB, CSIC and BIST, Barcelona,Bellaterra, 08193, Spain; ICREA, Instituci o Catalana de Recerca i Estudis Avancats, Barcelona, 08070, Spain; Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden, 01062, Germany; Dresden Center for Computational Materials Science and Center for Advancing Electronics Dresden, Dresden, 01062, Germany; Department of Micro-And Nanotechnology (DTU Nanotech), Center for Nanostructured Graphene (CNG), Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark; Max Planck Institute for Physics of Complex Systems, Dresden, 01187, Germany},
      abstract={With the advances in fabrication of materials with feature sizes at the order of nanometers, it has been possible to alter their thermal transport properties dramatically. Miniaturization of device size increases the power density in general, hence faster electronics require better thermal transport, whereas better thermoelectric applications require the opposite. Such diverse needs bring new challenges for material design. Shrinkage of length scales has also changed the experimental and theoretical methods to study thermal transport. Unsurprisingly, novel approaches have emerged to control phonon flow. Besides, ever increasing computational power is another driving force for developing new computational methods. In this review, we discuss three methods developed for computing vibrational thermal transport properties of nano-structured systems, namely Green function, quasi-classical Langevin, and Kubo-Green methods. The Green function methods are explained using both nonequilibrium expressions and the Landauer-type formula. The partitioning scheme, decimation techniques and surface Green functions are reviewed, and a simple model for reservoir Green functions is shown. The expressions for the Kubo-Greenwood method are derived, and Lanczos tridiagonalization, continued fraction and Chebyshev polynomial expansion methods are discussed. Additionally, the quasi-classical Langevin approach, which is useful for incorporating phonon-phonon and other scatterings is summarized. © 2019 IOP Publishing Ltd.},
      author_keywords={Green function method; Kubo-greenwood method; Quantum thermal transport; Quasi-classical langevin method},
      keywords={Green computing; Green's function; Phonons; Polynomials; Transport properties, Chebyshev polynomial expansion; Kubo-greenwood method; Lanczos tridiagonalization; Langevin method; Miniaturization of devices; Thermal transport; Thermal transport properties; Thermoelectric application, Quantum chemistry},
      publisher={Institute of Physics Publishing},
      issn={09538984},
      coden={JCOME},
      pubmed_id={31026228},
      language={English},
      abbrev_source_title={J Phys Condens Matter},
      document_type={Review},
      source={Scopus},
      }

  • Impact of device geometry on electron and phonon transport in graphene nanorings
    • M. Saiz-Bretín, L. Medrano Sandonas, R. Gutierrez, G. Cuniberti, F. Domínguez-Adame
    • Physical Review B 99, 165428 (2019)
    • DOI   Abstract  

      Recent progress in nanostructuring of materials opens up possibilities to achieve more efficient thermoelectric devices. Nanofilms, nanowires, and nanorings may show increased phonon scattering while keeping good electron transport, two of the basic ingredients for designing more efficient thermoelectric systems. Here we argue that graphene nanorings attached to two leads meet these two requirements. Using a density-functional parametrized tight-binding method combined with Green’s function technique, we show that the lattice thermal conductance is largely reduced as compared to that of graphene nanoribbons. At the same time, numerical calculations based on the quantum transmission boundary method, combined with an effective transfer matrix method, predict that the electric properties are not considerably deteriorated, leading to an overall remarkable thermoelectric efficiency. We conclude that graphene nanorings can be regarded as promising candidates for nanoscale thermoelectric devices. © 2019 American Physical Society.

      @ARTICLE{Saiz-Bretín2019,
      author={Saiz-Bretín, M. and Medrano Sandonas, L. and Gutierrez, R. and Cuniberti, G. and Domínguez-Adame, F.},
      title={Impact of device geometry on electron and phonon transport in graphene nanorings},
      journal={Physical Review B},
      year={2019},
      volume={99},
      number={16},
      doi={10.1103/PhysRevB.99.165428},
      art_number={165428},
      note={cited By 5},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065238895&doi=10.1103%2fPhysRevB.99.165428&partnerID=40&md5=c3cdf07ce468a27d42f7fcc761b144d0},
      affiliation={GISC, Departamento de Física de Materiales, Universidad Complutense, Madrid, E-28040, Spain; Institute for Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany},
      abstract={Recent progress in nanostructuring of materials opens up possibilities to achieve more efficient thermoelectric devices. Nanofilms, nanowires, and nanorings may show increased phonon scattering while keeping good electron transport, two of the basic ingredients for designing more efficient thermoelectric systems. Here we argue that graphene nanorings attached to two leads meet these two requirements. Using a density-functional parametrized tight-binding method combined with Green's function technique, we show that the lattice thermal conductance is largely reduced as compared to that of graphene nanoribbons. At the same time, numerical calculations based on the quantum transmission boundary method, combined with an effective transfer matrix method, predict that the electric properties are not considerably deteriorated, leading to an overall remarkable thermoelectric efficiency. We conclude that graphene nanorings can be regarded as promising candidates for nanoscale thermoelectric devices. © 2019 American Physical Society.},
      keywords={Electron transport properties; Graphene; Nanoribbons; Nanorings; Nanostructured materials; Numerical methods; Phonons; Transfer matrix method, Electron and phonon transports; Green's function technique; Numerical calculation; Quantum transmission; Thermoelectric devices; Thermoelectric efficiency; Thermoelectric systems; Tight binding methods, Graphene devices},
      publisher={American Physical Society},
      issn={24699950},
      language={English},
      abbrev_source_title={Phys. Rev. B},
      document_type={Article},
      source={Scopus},
      }

  • An efficient numerical framework for the amplitude expansion of the phase-field crystal model
    • S. Praetorius, M. Salvalaglio, A. Voigt
    • Modelling and Simulation in Materials Science and Engineering 27, 044004 (2019)
    • DOI   Abstract  

      The study of polycrystalline materials requires theoretical and computational techniques enabling multiscale investigations. The amplitude expansion of the phase-field crystal model allows for describing crystal lattice properties on diffusive timescales by focusing on continuous fields varying on length scales larger than the atomic spacing. Thus, it allows for the simulation of large systems still retaining details of the crystal lattice. Fostered by the applications of this approach, we present here an efficient numerical framework to solve its equations. In particular, we consider a real space approach exploiting the finite element method. An optimized preconditioner is developed in order to improve the convergence of the linear solver. Moreover, a mesh adaptivity criterion based on the local rotation of the polycrystal is used. This results in an unprecedented capability of simulating large, three-dimensional systems including the dynamical description of the microstructures in polycrystalline materials together with their dislocation networks. © 2019 IOP Publishing Ltd.

      @ARTICLE{Praetorius2019,
      author={Praetorius, S. and Salvalaglio, M. and Voigt, A.},
      title={An efficient numerical framework for the amplitude expansion of the phase-field crystal model},
      journal={Modelling and Simulation in Materials Science and Engineering},
      year={2019},
      volume={27},
      number={4},
      doi={10.1088/1361-651X/ab1508},
      art_number={044004},
      note={cited By 11},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064274891&doi=10.1088%2f1361-651X%2fab1508&partnerID=40&md5=8937dd6824447312ea5d07c95a356ae9},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, D-01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, D-01062, Germany},
      abstract={The study of polycrystalline materials requires theoretical and computational techniques enabling multiscale investigations. The amplitude expansion of the phase-field crystal model allows for describing crystal lattice properties on diffusive timescales by focusing on continuous fields varying on length scales larger than the atomic spacing. Thus, it allows for the simulation of large systems still retaining details of the crystal lattice. Fostered by the applications of this approach, we present here an efficient numerical framework to solve its equations. In particular, we consider a real space approach exploiting the finite element method. An optimized preconditioner is developed in order to improve the convergence of the linear solver. Moreover, a mesh adaptivity criterion based on the local rotation of the polycrystal is used. This results in an unprecedented capability of simulating large, three-dimensional systems including the dynamical description of the microstructures in polycrystalline materials together with their dislocation networks. © 2019 IOP Publishing Ltd.},
      author_keywords={coarse graining; dislocations; finite element method; grain boundaries; phase field crystal; phase field modeling; polycrystalline growth},
      keywords={Crystal lattices; Dislocations (crystals); Grain boundaries; Polycrystalline materials, Coarse Graining; Computational technique; Dislocation networks; Phase field crystal model; Phase field models; Phase-field crystals; Polycrystalline growth; Three dimensional systems, Finite element method},
      publisher={Institute of Physics Publishing},
      issn={09650393},
      coden={MSMEE},
      language={English},
      abbrev_source_title={Modell Simul Mater Sci Eng},
      document_type={Article},
      source={Scopus},
      }

  • Selective Transmission of Phonons in Molecular Junctions with Nanoscopic Thermal Baths
    • L. Medrano Sandonas, A. Rodríguez Méndez, R. Gutierrez, J. M. Ugalde, V. Mujica, G. Cuniberti
    • Journal of Physical Chemistry C 123, 9680-9687 (2019)
    • DOI   Abstract  

      A fundamental problem for thermal energy harvesting is the development of atomistic design strategies for smart nanodevices and nanomaterials that can be used to selectively transmit heat. We carry out here an extensive computational study demonstrating that heterogeneous molecular junctions, consisting of molecular wires bridging two different nanocontacts, can act as a selective phonon filter. The most important finding is the appearance of gaps on the phonon transmittance spectrum, which are strongly correlated to the properties of the vibrational spectrum of the specific molecular species in the junction. The filtering effect results from a delicate interplay between the intrinsic vibrational structure of the molecular chains and the different Debye cutoffs of the nanoscopic electrodes used as thermal baths. Copyright © 2019 American Chemical Society.

      @ARTICLE{MedranoSandonas20199680,
      author={Medrano Sandonas, L. and Rodríguez Méndez, A. and Gutierrez, R. and Ugalde, J.M. and Mujica, V. and Cuniberti, G.},
      title={Selective Transmission of Phonons in Molecular Junctions with Nanoscopic Thermal Baths},
      journal={Journal of Physical Chemistry C},
      year={2019},
      volume={123},
      number={15},
      pages={9680-9687},
      doi={10.1021/acs.jpcc.8b11879},
      note={cited By 7},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064338979&doi=10.1021%2facs.jpcc.8b11879&partnerID=40&md5=30bde626e92df12c89fa1da90359a33d},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Kimika Fakultatea, Euskal Herriko Unibertsitatea (UPV/EHU), P.K. 1072, Euskadi, Donostia, 20080, Spain; Donostia International Physics Center (DIPC), P.K. 1072, Euskadi, Donostia, 20080, Spain; School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, United States; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={A fundamental problem for thermal energy harvesting is the development of atomistic design strategies for smart nanodevices and nanomaterials that can be used to selectively transmit heat. We carry out here an extensive computational study demonstrating that heterogeneous molecular junctions, consisting of molecular wires bridging two different nanocontacts, can act as a selective phonon filter. The most important finding is the appearance of gaps on the phonon transmittance spectrum, which are strongly correlated to the properties of the vibrational spectrum of the specific molecular species in the junction. The filtering effect results from a delicate interplay between the intrinsic vibrational structure of the molecular chains and the different Debye cutoffs of the nanoscopic electrodes used as thermal baths. Copyright © 2019 American Chemical Society.},
      keywords={Energy harvesting; Nanostructured materials, Computational studies; Design strategies; Molecular junction; Molecular species; Selective transmissions; Smart nanodevices; Transmittance spectra; Vibrational structures, Phonons},
      correspondence_address1={Gutierrez, R.; Institute for Materials Science, Germany; email: rafael.gutierrez@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19327447},
      language={English},
      abbrev_source_title={J. Phys. Chem. C},
      document_type={Article},
      source={Scopus},
      }

  • Electron Transport through Self-Assembled Monolayers of Tripeptides
    • E. Mervinetsky, I. Alshanski, S. Lenfant, D. Guerin, L. Medrano Sandonas, A. Dianat, R. Gutierrez, G. Cuniberti, M. Hurevich, S. Yitzchaik, D. Vuillaume
    • Journal of Physical Chemistry C 123, 9600-9608 (2019)
    • DOI   Abstract  

      We report how the electron transport through a solid-state metal/Gly-Gly-His (GGH) tripeptide monolayer/metal junction and the metal/GGH work function (WF) are modified by the GGH complexation with Cu2+ ions. Conducting atomic force microscopy is used to measure the current-voltage histograms. The WF is characterized by combining macroscopic Kelvin probe and Kelvin probe force microscopy at the nanoscale. We observe that the complexation of Cu2+ ions with the GGH monolayer is highly dependent on the molecular surface density and results in opposite trends. In the case of a high-density monolayer the conformational changes are hindered by the proximity of the neighboring peptides, hence forming an insulating layer in response to copper complexation. However, the monolayers of a slightly lower density allow for the conformational change to a looped peptide wrapping the Cu-ion, which results in a more conductive monolayer. Copper-ion complexation to the high- and low-density monolayers systematically induces an increase of the WFs. Copper-ion complexation to the low-density monolayer induces an increase of electron-transport efficiency, whereas the copper-ion complexation to the high-density monolayer results in a slight decrease of electron transport. Both of the observed trends agree with first-principle calculations. Complexation of copper to the low-density GGH monolayer induces a new gap state slightly above the Au Fermi energy that is absent in the high-density monolayer. © Copyright © 2019 American Chemical Society.

      @ARTICLE{Mervinetsky20199600,
      author={Mervinetsky, E. and Alshanski, I. and Lenfant, S. and Guerin, D. and Medrano Sandonas, L. and Dianat, A. and Gutierrez, R. and Cuniberti, G. and Hurevich, M. and Yitzchaik, S. and Vuillaume, D.},
      title={Electron Transport through Self-Assembled Monolayers of Tripeptides},
      journal={Journal of Physical Chemistry C},
      year={2019},
      volume={123},
      number={14},
      pages={9600-9608},
      doi={10.1021/acs.jpcc.9b01082},
      note={cited By 11},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064275523&doi=10.1021%2facs.jpcc.9b01082&partnerID=40&md5=ea033e76ecce5343d65dd5c268fdad43},
      affiliation={Institute of Chemistry, Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem, 91904, Israel; Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Safra Campus, Jerusalem, 91904, Israel; Institute for Electronics Microelectronics and Nanotechnology, CNRS, Université de Lille, Villeneuve d'Ascq, 59652, France; Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01069, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={We report how the electron transport through a solid-state metal/Gly-Gly-His (GGH) tripeptide monolayer/metal junction and the metal/GGH work function (WF) are modified by the GGH complexation with Cu2+ ions. Conducting atomic force microscopy is used to measure the current-voltage histograms. The WF is characterized by combining macroscopic Kelvin probe and Kelvin probe force microscopy at the nanoscale. We observe that the complexation of Cu2+ ions with the GGH monolayer is highly dependent on the molecular surface density and results in opposite trends. In the case of a high-density monolayer the conformational changes are hindered by the proximity of the neighboring peptides, hence forming an insulating layer in response to copper complexation. However, the monolayers of a slightly lower density allow for the conformational change to a looped peptide wrapping the Cu-ion, which results in a more conductive monolayer. Copper-ion complexation to the high- and low-density monolayers systematically induces an increase of the WFs. Copper-ion complexation to the low-density monolayer induces an increase of electron-transport efficiency, whereas the copper-ion complexation to the high-density monolayer results in a slight decrease of electron transport. Both of the observed trends agree with first-principle calculations. Complexation of copper to the low-density GGH monolayer induces a new gap state slightly above the Au Fermi energy that is absent in the high-density monolayer. © Copyright © 2019 American Chemical Society.},
      keywords={Atomic force microscopy; Complexation; Electron transport properties; Heavy ions; Metal ions; Peptides; Probes; Self assembled monolayers, Conducting atomic force microscopy; Conformational change; Copper complexation; Copper ion complexation; Electron transport; First principle calculations; Kelvin probe force microscopy; Molecular surfaces, Copper compounds},
      correspondence_address1={Vuillaume, D.; Institute for Electronics Microelectronics and Nanotechnology, France; email: dominique.vuillaume@iemn.fr},
      publisher={American Chemical Society},
      issn={19327447},
      language={English},
      abbrev_source_title={J. Phys. Chem. C},
      document_type={Article},
      source={Scopus},
      }

  • Magnetic anisotropy and spin-polarized two-dimensional electron gas in the van der Waals ferromagnet Cr2Ge2Te6
    • J. Zeisner, A. Alfonsov, S. Selter, S. Aswartham, M. P. Ghimire, M. Richter, J. Van Den Brink, B. Büchner, V. Kataev
    • Physical Review B 99, 165109 (2019)
    • DOI   Abstract  

      We report a comprehensive experimental investigation on the magnetic anisotropy in bulk single crystals of Cr2Ge2Te6, a quasi-two-dimensional ferromagnet belonging to the family of magnetic layered transition metal trichalcogenides that have recently attracted a great deal of interest with regard to the fundamental and applied aspects of two-dimensional magnetism. For this purpose electron spin resonance (ESR) and ferromagnetic resonance (FMR) measurements have been carried out over a wide frequency and temperature range. A gradual change in the angular dependence of the ESR linewidth at temperatures above the ferromagnetic transition temperature Tc reveals the development of two-dimensional spin correlations in the vicinity of Tc thereby proving the intrinsically low-dimensional character of spin dynamics in Cr2Ge2Te6. Angular and frequency dependent measurements in the ferromagnetic phase clearly show an easy-axis-type anisotropy of this compound. Furthermore, these experiments are compared with simulations based on a phenomenological approach, which takes into account results of static magnetization measurements as well as high temperature g factors obtained from ESR spectroscopy in the paramagnetic phase. As a result the determined magnetocrystalline anisotropy energy density (MAE) KU is (0.48±0.02)×106 erg/cm3. This analysis is complemented by density functional calculations which yield the experimental MAE value for a particular value of the electronic correlation strength U. The analysis of the electronic structure reveals that the low-lying conduction band carries almost completely spin-polarized, quasihomogeneous, two-dimensional states. © 2019 American Physical Society.

      @ARTICLE{Zeisner2019,
      author={Zeisner, J. and Alfonsov, A. and Selter, S. and Aswartham, S. and Ghimire, M.P. and Richter, M. and Van Den Brink, J. and Büchner, B. and Kataev, V.},
      title={Magnetic anisotropy and spin-polarized two-dimensional electron gas in the van der Waals ferromagnet Cr2Ge2Te6},
      journal={Physical Review B},
      year={2019},
      volume={99},
      number={16},
      doi={10.1103/PhysRevB.99.165109},
      art_number={165109},
      note={cited By 37},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064133163&doi=10.1103%2fPhysRevB.99.165109&partnerID=40&md5=0dd243ad52010b0e4a95b080ae0ab8f1},
      affiliation={Leibniz Institute for Solid State and Materials Research IFW Dresden, Dresden, 01069, Germany; Institute for Solid State and Materials Physics, TU Dresden, Dresden, 01062, Germany; Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, 44613, Nepal; Condensed Matter Physics Research Center, Butwal-11, Rupandehi, Lumbini, Nepal; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={We report a comprehensive experimental investigation on the magnetic anisotropy in bulk single crystals of Cr2Ge2Te6, a quasi-two-dimensional ferromagnet belonging to the family of magnetic layered transition metal trichalcogenides that have recently attracted a great deal of interest with regard to the fundamental and applied aspects of two-dimensional magnetism. For this purpose electron spin resonance (ESR) and ferromagnetic resonance (FMR) measurements have been carried out over a wide frequency and temperature range. A gradual change in the angular dependence of the ESR linewidth at temperatures above the ferromagnetic transition temperature Tc reveals the development of two-dimensional spin correlations in the vicinity of Tc thereby proving the intrinsically low-dimensional character of spin dynamics in Cr2Ge2Te6. Angular and frequency dependent measurements in the ferromagnetic phase clearly show an easy-axis-type anisotropy of this compound. Furthermore, these experiments are compared with simulations based on a phenomenological approach, which takes into account results of static magnetization measurements as well as high temperature g factors obtained from ESR spectroscopy in the paramagnetic phase. As a result the determined magnetocrystalline anisotropy energy density (MAE) KU is (0.48±0.02)×106 erg/cm3. This analysis is complemented by density functional calculations which yield the experimental MAE value for a particular value of the electronic correlation strength U. The analysis of the electronic structure reveals that the low-lying conduction band carries almost completely spin-polarized, quasihomogeneous, two-dimensional states. © 2019 American Physical Society.},
      keywords={Electron gas; Electronic structure; Electrospinning; Ferromagnetic materials; Ferromagnetic resonance; Ferromagnetism; Magnetic anisotropy; Magnetic moments; Magnetocrystalline anisotropy; Magnets; Single crystals; Spin dynamics; Spin polarization; Superconducting materials; Technetium; Two dimensional electron gas; Van der Waals forces, Electronic correlation; Experimental investigations; Ferromagnetic resonance measurements; Ferromagnetic transition temperatures; Frequency-dependent measurements; Magnetocrystalline anisotropy energy density; Phenomenological approach; Static magnetization, Electron spin resonance spectroscopy},
      publisher={American Physical Society},
      issn={24699950},
      language={English},
      abbrev_source_title={Phys. Rev. B},
      document_type={Article},
      source={Scopus},
      }

  • Towards infinite tilings with symmetric boundaries
    • F. Stenger, A. Voigt
    • Symmetry 11, 444 (2019)
    • DOI   Abstract  

      Large-time coarsening and the associated scaling and statistically self-similar properties are used to construct infinite tilings. This is realized using a Cahn-Hilliard equation and special boundaries on each tile. Within a compromise between computational effort and the goal to reduce recurrences, an infinite tiling has been created and software which zooms in and out evolve forward and backward in time as well as traverse the infinite tiling horizontally and vertically. We also analyze the scaling behavior and the statistically self-similar properties and describe the numerical approach, which is based on finite elements and an energy-stable time discretization. © 2019 by the authors.

      @ARTICLE{Stenger2019,
      author={Stenger, F. and Voigt, A.},
      title={Towards infinite tilings with symmetric boundaries},
      journal={Symmetry},
      year={2019},
      volume={11},
      number={4},
      doi={10.3390/sym11040444},
      art_number={444},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065493258&doi=10.3390%2fsym11040444&partnerID=40&md5=6fb671413f33c29c7da454a183855f5c},
      affiliation={Institute of Scientific Computing, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Large-time coarsening and the associated scaling and statistically self-similar properties are used to construct infinite tilings. This is realized using a Cahn-Hilliard equation and special boundaries on each tile. Within a compromise between computational effort and the goal to reduce recurrences, an infinite tiling has been created and software which zooms in and out evolve forward and backward in time as well as traverse the infinite tiling horizontally and vertically. We also analyze the scaling behavior and the statistically self-similar properties and describe the numerical approach, which is based on finite elements and an energy-stable time discretization. © 2019 by the authors.},
      author_keywords={Computational design; Finite-element method; Pattern formation; Symmetric boundary condition},
      correspondence_address1={Voigt, A.; Institute of Scientific Computing, Germany; email: axel.voigt@tu-dresden.de},
      publisher={MDPI AG},
      issn={20738994},
      language={English},
      abbrev_source_title={Symmetry},
      document_type={Article},
      source={Scopus},
      }

  • Hydrodynamic interactions in polar liquid crystals on evolving surfaces
    • I. Nitschke, S. Reuther, A. Voigt
    • Physical Review Fluids 4, 044002 (2019)
    • DOI   Abstract  

      We consider the derivation and numerical solution of the flow of passive and active polar liquid crystals, whose molecular orientation is subjected to a tangential anchoring on an evolving curved surface. The underlying passive model is a simplified surface Ericksen-Leslie model, which is derived as a thin-film limit of the corresponding three-dimensional equations with appropriate boundary conditions. A finite element discretization is considered and the effect of hydrodynamics on the interplay of topology, geometric properties, and defect dynamics is studied for this model on various stationary and evolving surfaces. Additionally, we consider an active model. We propose a surface formulation for an active polar viscous gel and exemplarily demonstrate the effect of the underlying curvature on the location of topological defects on a torus. © 2019 American Physical Society..

      @ARTICLE{Nitschke2019,
      author={Nitschke, I. and Reuther, S. and Voigt, A.},
      title={Hydrodynamic interactions in polar liquid crystals on evolving surfaces},
      journal={Physical Review Fluids},
      year={2019},
      volume={4},
      number={4},
      doi={10.1103/PhysRevFluids.4.044002},
      art_number={044002},
      note={cited By 21},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85065031797&doi=10.1103%2fPhysRevFluids.4.044002&partnerID=40&md5=16212f8eb3948fc837615eade901f63a},
      affiliation={Institute of Scientific Computing, Technische Universität, Dresden, Germany; Institute of Scientific Computing, Technische Universität Dresden, Dresden Center for Computational Materials Science (DCMS), Center for Systems Biology Dresden (CSBD), Cluster of Excellence Physics of Life (PoL), Dresden, Germany},
      abstract={We consider the derivation and numerical solution of the flow of passive and active polar liquid crystals, whose molecular orientation is subjected to a tangential anchoring on an evolving curved surface. The underlying passive model is a simplified surface Ericksen-Leslie model, which is derived as a thin-film limit of the corresponding three-dimensional equations with appropriate boundary conditions. A finite element discretization is considered and the effect of hydrodynamics on the interplay of topology, geometric properties, and defect dynamics is studied for this model on various stationary and evolving surfaces. Additionally, we consider an active model. We propose a surface formulation for an active polar viscous gel and exemplarily demonstrate the effect of the underlying curvature on the location of topological defects on a torus. © 2019 American Physical Society..},
      keywords={Crystal orientation; Hydrodynamics; Liquid crystals; Molecular orientation, Ericksen-Leslie model; Finite-element discretization; Geometric properties; Hydrodynamic interaction; Numerical solution; Polar liquid crystals; Three-dimensional equations; Topological defect, Topology},
      correspondence_address1={Reuther, S.; Institute of Scientific Computing, Germany; email: sebastian.reuther@tu-dresden.de},
      publisher={American Physical Society},
      issn={2469990X},
      language={English},
      abbrev_source_title={Phys. Rev. Fluids},
      document_type={Article},
      source={Scopus},
      }

  • Thermal bridging of graphene nanosheets via covalent molecular junctions: A non-equilibrium Green’s functions–density functional tight-binding study
    • D. Martinez Gutierrez, A. Di Pierro, A. Pecchia, L. M. Sandonas, R. Gutierrez, M. Bernal, B. Mortazavi, G. Cuniberti, G. Saracco, A. Fina
    • Nano Research 12, 791-799 (2019)
    • DOI   Abstract  

      Despite the uniquely high thermal conductivity of graphene is well known, the exploitation of graphene into thermally conductive nanomaterials and devices is limited by the inefficiency of thermal contacts between the individual nanosheets. A fascinating yet experimentally challenging route to enhance thermal conductance at contacts between graphene nanosheets is through molecular junctions, allowing covalently connecting nanosheets, otherwise interacting only via weak Van der Waals forces. Beside the bare existence of covalent connections, the choice of molecular structures to be used as thermal junctions should be guided by their vibrational properties, in terms of phonon transfer through the molecular junction. In this paper, density functional tight-binding combined with Green’s functions formalism was applied for the calculation of thermal conductance and phonon spectra of several different aliphatic and aromatic molecular junctions between graphene nanosheets. Effects of molecular junction length, conformation, and aromaticity were studied in detail and correlated with phonon tunnelling spectra. The theoretical insight provided by this work can guide future experimental studies to select suitable molecular junctions, in order to enhance the thermal transport by suppressing the interfacial thermal resistances. This is attractive for various systems, including graphene nanopapers and graphene polymer nanocomposites, as well as related devices. In a broader view, the possibility to design molecular junctions to control phonon transport currently appears as an efficient way to produce phononic devices and controlling heat management in nanostructures. [Figure not available: see fulltext.]. © 2019, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature.

      @ARTICLE{MartinezGutierrez2019791,
      author={Martinez Gutierrez, D. and Di Pierro, A. and Pecchia, A. and Sandonas, L.M. and Gutierrez, R. and Bernal, M. and Mortazavi, B. and Cuniberti, G. and Saracco, G. and Fina, A.},
      title={Thermal bridging of graphene nanosheets via covalent molecular junctions: A non-equilibrium Green’s functions–density functional tight-binding study},
      journal={Nano Research},
      year={2019},
      volume={12},
      number={4},
      pages={791-799},
      doi={10.1007/s12274-019-2290-2},
      note={cited By 27},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062153066&doi=10.1007%2fs12274-019-2290-2&partnerID=40&md5=84cc9f2a6c6dbfbb2018252d079682bd},
      affiliation={Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Alessandria, 15121, Italy; Consiglio Nazionale delle Ricerche, ISMN, Monterotondo, 00017, Italy; Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Institute of Structural Mechanics, Bauhaus-Universität Weimar, Weimar, D-99423, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany},
      abstract={Despite the uniquely high thermal conductivity of graphene is well known, the exploitation of graphene into thermally conductive nanomaterials and devices is limited by the inefficiency of thermal contacts between the individual nanosheets. A fascinating yet experimentally challenging route to enhance thermal conductance at contacts between graphene nanosheets is through molecular junctions, allowing covalently connecting nanosheets, otherwise interacting only via weak Van der Waals forces. Beside the bare existence of covalent connections, the choice of molecular structures to be used as thermal junctions should be guided by their vibrational properties, in terms of phonon transfer through the molecular junction. In this paper, density functional tight-binding combined with Green’s functions formalism was applied for the calculation of thermal conductance and phonon spectra of several different aliphatic and aromatic molecular junctions between graphene nanosheets. Effects of molecular junction length, conformation, and aromaticity were studied in detail and correlated with phonon tunnelling spectra. The theoretical insight provided by this work can guide future experimental studies to select suitable molecular junctions, in order to enhance the thermal transport by suppressing the interfacial thermal resistances. This is attractive for various systems, including graphene nanopapers and graphene polymer nanocomposites, as well as related devices. In a broader view, the possibility to design molecular junctions to control phonon transport currently appears as an efficient way to produce phononic devices and controlling heat management in nanostructures. [Figure not available: see fulltext.]. © 2019, Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature.},
      author_keywords={density functional tight-binding (DFTB); graphene; Green’s functions; heat transport; molecular junctions; phonon transmission function; thermal conductance},
      keywords={Graphene; Graphene devices; Nanocomposites; Nanosheets; Phonons; Van der Waals forces, Density functional tight bindings; Heat transport; Molecular junction; Phonon transmissions; S function; Thermal conductance, Thermal conductivity},
      correspondence_address1={Fina, A.; Dipartimento di Scienza Applicata e Tecnologia, Italy; email: alberto.fina@polito.it},
      publisher={Tsinghua University Press},
      issn={19980124},
      language={English},
      abbrev_source_title={Nano. Res.},
      document_type={Article},
      source={Scopus},
      }

  • Radially resolved electronic structure and charge carrier transport in silicon nanowires
    • F. Fuchs, S. Gemming, J. Schuster
    • Physica E: Low-Dimensional Systems and Nanostructures 108, 181-186 (2019)
    • DOI   Abstract  

      The electronic structure of silicon nanowires is studied using density functional theory. A radially resolved density of states is discussed for different nanowire diameters and crystal orientations. This approach allows the investigation of spatially varying electronic properties in the radial direction and extends previous studies, which are usually driven by a one-dimensional band structure analysis. We demonstrate strong differences in the electronic structure between the surface and the center of the nanowire, indicating that the carrier transport will mainly take place in the center. For increasing diameters, the density of states in the center approaches the bulk density of states. We find that bulk properties, such as the indirect nature of the band gap, become significant at a nanowire diameter of approximately 5 nm and beyond. Finally, the spatial characteristic of the current is visualized in terms of transmission pathways on the atomic scale. Electron transport is found to be more localized in the nanowire center than the hole transport. It also depends on the crystal orientation of the wire. For the growing demand of silicon nanowires, for example in the field of sensors or field-effect transistors, multiple conclusions can be drawn from the present work, which we discuss towards the end of the publication. © 2018 Elsevier B.V.

      @ARTICLE{Fuchs2019181,
      author={Fuchs, F. and Gemming, S. and Schuster, J.},
      title={Radially resolved electronic structure and charge carrier transport in silicon nanowires},
      journal={Physica E: Low-Dimensional Systems and Nanostructures},
      year={2019},
      volume={108},
      pages={181-186},
      doi={10.1016/j.physe.2018.12.002},
      note={cited By 6},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059062217&doi=10.1016%2fj.physe.2018.12.002&partnerID=40&md5=e804cb3aaeeb039dbebef68ccf872dcc},
      affiliation={Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Dresden, Germany; Center for Advancing Electronics Dresden, Dresden, Germany; Institute of Physics, Chemnitz University of Technology, Chemnitz, Germany; Fraunhofer Institute for Electronic Nano Systems, Chemnitz, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, Germany},
      abstract={The electronic structure of silicon nanowires is studied using density functional theory. A radially resolved density of states is discussed for different nanowire diameters and crystal orientations. This approach allows the investigation of spatially varying electronic properties in the radial direction and extends previous studies, which are usually driven by a one-dimensional band structure analysis. We demonstrate strong differences in the electronic structure between the surface and the center of the nanowire, indicating that the carrier transport will mainly take place in the center. For increasing diameters, the density of states in the center approaches the bulk density of states. We find that bulk properties, such as the indirect nature of the band gap, become significant at a nanowire diameter of approximately 5 nm and beyond. Finally, the spatial characteristic of the current is visualized in terms of transmission pathways on the atomic scale. Electron transport is found to be more localized in the nanowire center than the hole transport. It also depends on the crystal orientation of the wire. For the growing demand of silicon nanowires, for example in the field of sensors or field-effect transistors, multiple conclusions can be drawn from the present work, which we discuss towards the end of the publication. © 2018 Elsevier B.V.},
      keywords={Carrier transport; Density functional theory; Electron transport properties; Electronic properties; Electronic structure; Energy gap; Field effect transistors; Nanowires; Silicon, Band structure analysis; Bulk properties; Density of state; Electron transport; Hole transports; Radial direction; Silicon nanowires; Spatial characteristics, Crystal orientation},
      correspondence_address1={Fuchs, F.; Institute of Physics, Germany; email: florian.fuchs@physik.tu-chemnitz.de},
      publisher={Elsevier B.V.},
      issn={13869477},
      coden={PELNF},
      language={English},
      abbrev_source_title={Phys E},
      document_type={Article},
      source={Scopus},
      }

  • Phase-field modelling of interface failure in brittle materials
    • A. C. Hansen-Dörr, R. de Borst, P. Hennig, M. Kästner
    • Computer Methods in Applied Mechanics and Engineering 346, 25-42 (2019)
    • DOI   Abstract  

      A phase-field approach is proposed for interface failure between two possibly dissimilar materials. The discrete adhesive interface is regularised over a finite width. Due to the use of a regularised crack model for the bulk material, an interaction between the length scales of the crack and the interface can occur. An analytic one-dimensional analysis has been carried out to quantify this effect and a correction is proposed, which compensates influences due to the regularisation in the bulk material. For multi-dimensional analyses this approach cannot be used straightforwardly, as is shown, and a study has been undertaken to numerically quantify the compensation factor due to the interaction. The aim is to obtain reliable and universally applicable results for crack propagation along interfaces between dissimilar materials, such that they are independent from the regularisation width of the interface. The method has been tested and validated on three benchmark problems. The compensation is particularly relevant for phase-field analyses in heterogeneous materials, where cohesive failure in the constituent materials as well as adhesive failure at interfaces play a role. © 2018 Elsevier B.V.

      @ARTICLE{Hansen-Dörr201925,
      author={Hansen-Dörr, A.C. and de Borst, R. and Hennig, P. and Kästner, M.},
      title={Phase-field modelling of interface failure in brittle materials},
      journal={Computer Methods in Applied Mechanics and Engineering},
      year={2019},
      volume={346},
      pages={25-42},
      doi={10.1016/j.cma.2018.11.020},
      note={cited By 57},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058511064&doi=10.1016%2fj.cma.2018.11.020&partnerID=40&md5=8e8694ffcdd269024efde18ff87823cd},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, Germany; University of Sheffield, Department of Civil and Structural Engineering, Mappin Street, Sir Frederick Mappin Building, Sheffield, S1 3JD, United Kingdom},
      abstract={A phase-field approach is proposed for interface failure between two possibly dissimilar materials. The discrete adhesive interface is regularised over a finite width. Due to the use of a regularised crack model for the bulk material, an interaction between the length scales of the crack and the interface can occur. An analytic one-dimensional analysis has been carried out to quantify this effect and a correction is proposed, which compensates influences due to the regularisation in the bulk material. For multi-dimensional analyses this approach cannot be used straightforwardly, as is shown, and a study has been undertaken to numerically quantify the compensation factor due to the interaction. The aim is to obtain reliable and universally applicable results for crack propagation along interfaces between dissimilar materials, such that they are independent from the regularisation width of the interface. The method has been tested and validated on three benchmark problems. The compensation is particularly relevant for phase-field analyses in heterogeneous materials, where cohesive failure in the constituent materials as well as adhesive failure at interfaces play a role. © 2018 Elsevier B.V.},
      author_keywords={Adhesive interface; Brittle fracture; Diffuse interface model; Interface failure; Phase-field modelling},
      keywords={Adhesives; Brittle fracture; Cracks; Dissimilar materials; Interfaces (materials); Materials handling equipment, Adhesive interfaces; Diffuse interface models; Heterogeneous materials; Interface failure; Multi-dimensional analysis; One-dimensional analysis; Phase field modelling; Phase-field approaches, Failure (mechanical)},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: markus.kaestner@tu-dresden.de},
      publisher={Elsevier B.V.},
      issn={00457825},
      coden={CMMEC},
      language={English},
      abbrev_source_title={Comput. Methods Appl. Mech. Eng.},
      document_type={Article},
      source={Scopus},
      }

  • Controlling Grain Boundaries by Magnetic Fields
    • R. Backofen, K. R. Elder, A. Voigt
    • Physical Review Letters 122, 126103 (2019)
    • DOI   Abstract  

      The ability to use external magnetic fields to influence the microstructure in polycrystalline materials has potential applications in microstructural engineering. To explore this potential and to understand the complex interactions between electromagnetic fields and solid-state matter transport we consider a phase-field-crystal model. Together with efficient and scalable numerical algorithms this allows the examination of the role that external magnetic fields play on the evolution of defect structures and grain boundaries, on diffusive timescales. Examples for planar and circular grain boundaries explain the essential atomistic processes and large scale simulations in 2D are used to obtain statistical data on grain growth under the influence of external fields. © 2019 American Physical Society.

      @ARTICLE{Backofen2019,
      author={Backofen, R. and Elder, K.R. and Voigt, A.},
      title={Controlling Grain Boundaries by Magnetic Fields},
      journal={Physical Review Letters},
      year={2019},
      volume={122},
      number={12},
      doi={10.1103/PhysRevLett.122.126103},
      art_number={126103},
      note={cited By 13},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064037815&doi=10.1103%2fPhysRevLett.122.126103&partnerID=40&md5=1734bd67d3dec6c981a3b8a5360e066e},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Department of Physics, Oakland University, Rochester, MI 48309, United States; Dresden Center for Computational Materials Science (DCMS), Dresden, 01062, Germany},
      abstract={The ability to use external magnetic fields to influence the microstructure in polycrystalline materials has potential applications in microstructural engineering. To explore this potential and to understand the complex interactions between electromagnetic fields and solid-state matter transport we consider a phase-field-crystal model. Together with efficient and scalable numerical algorithms this allows the examination of the role that external magnetic fields play on the evolution of defect structures and grain boundaries, on diffusive timescales. Examples for planar and circular grain boundaries explain the essential atomistic processes and large scale simulations in 2D are used to obtain statistical data on grain growth under the influence of external fields. © 2019 American Physical Society.},
      keywords={Electromagnetic fields; Grain growth; Magnetic fields; Polycrystalline materials, Atomistic process; Circular grains; External magnetic field; Large scale simulations; Microstructural engineering; Numerical algorithms; Phase field crystal model; Statistical datas, Grain boundaries},
      publisher={American Physical Society},
      issn={00319007},
      coden={PRLTA},
      pubmed_id={30978082},
      language={English},
      abbrev_source_title={Phys Rev Lett},
      document_type={Article},
      source={Scopus},
      }

  • Mapping Conformational Changes in a Self-Assembled Two-Dimensional Molecular Network by Statistical Analysis of Conductance Images
    • B. Naydenov, S. Torsney, A. S. Bonilla, A. Gualandi, L. Mengozzi, P. G. Cozzi, R. Gutierrez, G. Cuniberti, J. J. Boland
    • Physical Review Applied 11, 034070 (2019)
    • DOI   Abstract  

      A self-assembled two-dimensional (2D) film of tetra-phenyl-porphyrin-4-ferrocene molecules on Au(111) is studied by STM for the presence of intra- and intermolecular correlations in the configurations of the four-pendant ferrocenyl moieties. A statistical analysis of STS images exploits the Pearson’s linear correlation coefficient derived from changes in the molecular electron density across lateral positions in the molecular network as a measure of the intra- and intermolecular coupling and/or conjugation between adjacent equivalent molecular components. Density functional theory (DFT) calculation shows that these electron density changes can be assigned to conformational changes of the ferrocenyl units of the molecules. The methodology presented here can be extended to measure correlations in other 2D systems. © 2019 American Physical Society.

      @ARTICLE{Naydenov2019,
      author={Naydenov, B. and Torsney, S. and Bonilla, A.S. and Gualandi, A. and Mengozzi, L. and Cozzi, P.G. and Gutierrez, R. and Cuniberti, G. and Boland, J.J.},
      title={Mapping Conformational Changes in a Self-Assembled Two-Dimensional Molecular Network by Statistical Analysis of Conductance Images},
      journal={Physical Review Applied},
      year={2019},
      volume={11},
      number={3},
      doi={10.1103/PhysRevApplied.11.034070},
      art_number={034070},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064184651&doi=10.1103%2fPhysRevApplied.11.034070&partnerID=40&md5=1b0a636f91ef108325e4e76c34dc230f},
      affiliation={Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), School of Chemistry, Trinity College Dublin, Dublin 2, Ireland; Institute for Materials Sciences, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; ALMA MATER STUDIORUM UNIVERSITÀ di BOLOGNA, Dipartimento di Chimica G. Ciamician, Via Selmi 2, Bologna, 40126, Italy; Dresden Center for Computational Materials Science (DCCMS), TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={A self-assembled two-dimensional (2D) film of tetra-phenyl-porphyrin-4-ferrocene molecules on Au(111) is studied by STM for the presence of intra- and intermolecular correlations in the configurations of the four-pendant ferrocenyl moieties. A statistical analysis of STS images exploits the Pearson's linear correlation coefficient derived from changes in the molecular electron density across lateral positions in the molecular network as a measure of the intra- and intermolecular coupling and/or conjugation between adjacent equivalent molecular components. Density functional theory (DFT) calculation shows that these electron density changes can be assigned to conformational changes of the ferrocenyl units of the molecules. The methodology presented here can be extended to measure correlations in other 2D systems. © 2019 American Physical Society.},
      keywords={Carrier concentration; Conformations; Electron density measurement; Image analysis; Iron compounds; Molecules; Organometallics; Statistical methods, Conformational change; Intermolecular correlations; Intermolecular coupling; Linear correlation coefficient; Molecular components; Molecular electron density; Molecular networks; Two Dimensional (2 D), Density functional theory},
      publisher={American Physical Society},
      issn={23317019},
      language={English},
      abbrev_source_title={Phys. Rev. Appl.},
      document_type={Article},
      source={Scopus},
      }

  • Molecular parameters responsible for thermally activated transport in doped organic semiconductors
    • M. Schwarze, C. Gaul, R. Scholz, F. Bussolotti, A. Hofacker, K. S. Schellhammer, B. Nell, B. D. Naab, Z. Bao, D. Spoltore, K. Vandewal, J. Widmer, S. Kera, N. Ueno, F. Ortmann, K. Leo
    • Nature Materials 18, 242-248 (2019)
    • DOI   Abstract  

      Doped organic semiconductors typically exhibit a thermal activation of their electrical conductivity, whose physical origin is still under scientific debate. In this study, we disclose relationships between molecular parameters and the thermal activation energy (E A ) of the conductivity, revealing that charge transport is controlled by the properties of host–dopant integer charge transfer complexes (ICTCs) in efficiently doped organic semiconductors. At low doping concentrations, charge transport is limited by the Coulomb binding energy of ICTCs, which can be minimized by systematic modification of the charge distribution on the individual ions. The investigation of a wide variety of material systems reveals that static energetic disorder induced by ICTC dipole moments sets a general lower limit for E A at large doping concentrations. The impact of disorder can be reduced by adjusting the ICTC density and the intramolecular relaxation energy of host ions, allowing an increase of conductivity by many orders of magnitude. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.

      @ARTICLE{Schwarze2019242,
      author={Schwarze, M. and Gaul, C. and Scholz, R. and Bussolotti, F. and Hofacker, A. and Schellhammer, K.S. and Nell, B. and Naab, B.D. and Bao, Z. and Spoltore, D. and Vandewal, K. and Widmer, J. and Kera, S. and Ueno, N. and Ortmann, F. and Leo, K.},
      title={Molecular parameters responsible for thermally activated transport in doped organic semiconductors},
      journal={Nature Materials},
      year={2019},
      volume={18},
      number={3},
      pages={242-248},
      doi={10.1038/s41563-018-0277-0},
      note={cited By 85},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060809601&doi=10.1038%2fs41563-018-0277-0&partnerID=40&md5=c0df662b086e08611645bff185cfe69b},
      affiliation={Dresden Integrated Center for Applied Physics and Photonic Materials, Technische Universität Dresden, Dresden, Germany; Center for Advancing Electronics Dresden and Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany; Institute for Molecular Science, Department of Photo-Molecular Science, Myodaiji, Okazaki, Aichi, Japan; Department of Chemical Engineering, Stanford University, Stanford, CA, United States; Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan; Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Belgium; Heliatek GmbH, Dresden, Germany},
      abstract={Doped organic semiconductors typically exhibit a thermal activation of their electrical conductivity, whose physical origin is still under scientific debate. In this study, we disclose relationships between molecular parameters and the thermal activation energy (E A ) of the conductivity, revealing that charge transport is controlled by the properties of host–dopant integer charge transfer complexes (ICTCs) in efficiently doped organic semiconductors. At low doping concentrations, charge transport is limited by the Coulomb binding energy of ICTCs, which can be minimized by systematic modification of the charge distribution on the individual ions. The investigation of a wide variety of material systems reveals that static energetic disorder induced by ICTC dipole moments sets a general lower limit for E A at large doping concentrations. The impact of disorder can be reduced by adjusting the ICTC density and the intramolecular relaxation energy of host ions, allowing an increase of conductivity by many orders of magnitude. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.},
      keywords={Activation energy; Binding energy; Charge transfer, Charge transfer complex; Doping concentration; Electrical conductivity; Intramolecular relaxation; Low doping concentrations; Molecular parameters; Orders of magnitude; Thermal activation energies, Semiconductor doping},
      correspondence_address1={Schwarze, M.; Dresden Integrated Center for Applied Physics and Photonic Materials, Germany; email: martin.schwarze1@tu-dresden.de},
      publisher={Nature Publishing Group},
      issn={14761122},
      coden={NMAAC},
      pubmed_id={30692647},
      language={English},
      abbrev_source_title={Nat. Mater.},
      document_type={Article},
      source={Scopus},
      }

  • ITO Work Function Tunability by Polarizable Chromophore Monolayers
    • A. Gankin, E. Mervinetsky, I. Alshanski, J. Buchwald, A. Dianat, R. Gutierrez, G. Cuniberti, R. Sfez, S. Yitzchaik
    • Langmuir 35, 2997-3004 (2019)
    • DOI   Abstract  

      The ability to tune the electronic properties of oxide-bearing semiconductors such as Si/SiO 2 or transparent metal oxides such as indium-tin oxide (ITO) is of great importance in both electronic and optoelectronic device applications. In this work, we describe a process that was conducted on n-type Si/SiO 2 and ITO to induce changes in the substrate work function (WF). The substrates were modified by a two-step synthesis comprising a covalent attachment of coupling agents’ monolayer followed by in situ anchoring reactions of polarizable chromophores. The coupling agents and chromophores were chosen with opposite dipole orientations, which enabled the tunability of the substrates’ WF. In the first step, two coupling agents with opposite molecular dipole were assembled. The coupling agent with a negative dipole induced a decrease in WF of modified substrates, while the coupling agent with a positive dipole produced an increase in WFs of both ITO and Si substrates. The second modification step consisted of in situ anchoring reaction of polarizable chromophores with opposite dipoles to the coupling layer. This modification led to an additional change in the WFs of both Si/SiO 2 and ITO substrates. The WF was measured by contact potential difference and modeled by density functional theory-based theoretical calculations of the WF for each of the assembly steps. A good fit was obtained between the calculated and experimental trends. This ability to design and tune the WF of ITO substrates was implemented in an organic electronic device with improved I-V characteristics in comparison to a bare ITO-based device. © 2019 American Chemical Society.

      @ARTICLE{Gankin20192997,
      author={Gankin, A. and Mervinetsky, E. and Alshanski, I. and Buchwald, J. and Dianat, A. and Gutierrez, R. and Cuniberti, G. and Sfez, R. and Yitzchaik, S.},
      title={ITO Work Function Tunability by Polarizable Chromophore Monolayers},
      journal={Langmuir},
      year={2019},
      volume={35},
      number={8},
      pages={2997-3004},
      doi={10.1021/acs.langmuir.8b03943},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061934171&doi=10.1021%2facs.langmuir.8b03943&partnerID=40&md5=ed7dd51abfaa10b8a65a59b71f8b9a4f},
      affiliation={Institute of Chemistry, Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem, 91904, Israel; Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem, 91904, Israel; Azrieli College of Engineering, Jerusalem, 9103501, Israel; Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany},
      abstract={The ability to tune the electronic properties of oxide-bearing semiconductors such as Si/SiO 2 or transparent metal oxides such as indium-tin oxide (ITO) is of great importance in both electronic and optoelectronic device applications. In this work, we describe a process that was conducted on n-type Si/SiO 2 and ITO to induce changes in the substrate work function (WF). The substrates were modified by a two-step synthesis comprising a covalent attachment of coupling agents' monolayer followed by in situ anchoring reactions of polarizable chromophores. The coupling agents and chromophores were chosen with opposite dipole orientations, which enabled the tunability of the substrates' WF. In the first step, two coupling agents with opposite molecular dipole were assembled. The coupling agent with a negative dipole induced a decrease in WF of modified substrates, while the coupling agent with a positive dipole produced an increase in WFs of both ITO and Si substrates. The second modification step consisted of in situ anchoring reaction of polarizable chromophores with opposite dipoles to the coupling layer. This modification led to an additional change in the WFs of both Si/SiO 2 and ITO substrates. The WF was measured by contact potential difference and modeled by density functional theory-based theoretical calculations of the WF for each of the assembly steps. A good fit was obtained between the calculated and experimental trends. This ability to design and tune the WF of ITO substrates was implemented in an organic electronic device with improved I-V characteristics in comparison to a bare ITO-based device. © 2019 American Chemical Society.},
      keywords={Chromophores; Coupling agents; Density functional theory; Electronic properties; Monolayers; Optoelectronic devices; Silicon compounds; Tin oxides; Work function, Contact potential difference; Covalent attachment; Dipole orientation; ITO Work functions; IV characteristics; Organic electronic devices; Theoretical calculations; Two-step synthesis, Substrates},
      correspondence_address1={Gutierrez, R.; Institute for Materials Science, Germany; email: rafael.gutierrez@tu-dresden.de},
      publisher={American Chemical Society},
      issn={07437463},
      coden={LANGD},
      pubmed_id={30707589},
      language={English},
      abbrev_source_title={Langmuir},
      document_type={Article},
      source={Scopus},
      }

  • Strain and screening: Optical properties of a small-diameter carbon nanotube from first principles
    • C. Wagner, J. Schuster, A. Schleife
    • Physical Review B 99, 075140 (2019)
    • DOI   Abstract  

      Carbon nanotubes (CNTs) are a one-dimensional material system with intriguing physical properties that lead to emerging applications. While CNTs are unusually strain resistant compared to bulk materials, their optical-absorption spectrum is highly strain dependent. It is an open question, as to what extent this is attributed to strain-dependent (i) electronic single-particle transitions, (ii) dielectric screening, or (iii) atomic geometries including CNT radii. We use cutting-edge theoretical spectroscopy to explain strain-dependent electronic structure and optical properties of an (8,0) CNT. Quasiparticle effects are taken into account using Hedin’s GW approximation and excitonic effects are described by solving a Bethe-Salpeter-equation for the optical polarization function. This accurate first-principles approach allows us to identify an influence of strain on screening of the Coulomb electron-electron interaction and to quantify the impact on electronic structure and optical absorption of one-dimensional systems. We interpret our thoroughly converged results using an existing scaling relation and extend the use of this relation to strained CNTs. We show that it captures optical absorption with satisfactory accuracy, as long as screening, quasiparticle gap, and effective electron and hole masses of the strained CNT are known. © 2019 American Physical Society.

      @ARTICLE{Wagner2019,
      author={Wagner, C. and Schuster, J. and Schleife, A.},
      title={Strain and screening: Optical properties of a small-diameter carbon nanotube from first principles},
      journal={Physical Review B},
      year={2019},
      volume={99},
      number={7},
      doi={10.1103/PhysRevB.99.075140},
      art_number={075140},
      note={cited By 7},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061965955&doi=10.1103%2fPhysRevB.99.075140&partnerID=40&md5=475c52f453e41a693a4936f82c189e9e},
      affiliation={Technische Universität Chemnitz, Center for Microtechnologies, Reichenhainer Straße 70, Chemnitz, 09126, Germany; Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Fraunhofer Institute for Electronic Nano Systems (ENAS), Technologiecampus 3, Chemnitz, 09126, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, Dresden, 01328, Germany},
      abstract={Carbon nanotubes (CNTs) are a one-dimensional material system with intriguing physical properties that lead to emerging applications. While CNTs are unusually strain resistant compared to bulk materials, their optical-absorption spectrum is highly strain dependent. It is an open question, as to what extent this is attributed to strain-dependent (i) electronic single-particle transitions, (ii) dielectric screening, or (iii) atomic geometries including CNT radii. We use cutting-edge theoretical spectroscopy to explain strain-dependent electronic structure and optical properties of an (8,0) CNT. Quasiparticle effects are taken into account using Hedin's GW approximation and excitonic effects are described by solving a Bethe-Salpeter-equation for the optical polarization function. This accurate first-principles approach allows us to identify an influence of strain on screening of the Coulomb electron-electron interaction and to quantify the impact on electronic structure and optical absorption of one-dimensional systems. We interpret our thoroughly converged results using an existing scaling relation and extend the use of this relation to strained CNTs. We show that it captures optical absorption with satisfactory accuracy, as long as screening, quasiparticle gap, and effective electron and hole masses of the strained CNT are known. © 2019 American Physical Society.},
      keywords={Absorption spectroscopy; Electron-electron interactions; Electronic structure; Light absorption; Optical properties; Yarn, Bethe-Salpeter equation; Electronic structure and optical properties; First-principles approaches; One-dimensional materials; One-dimensional systems; Polarization functions; Small diameter carbon nanotubes; Theoretical spectroscopies, Carbon nanotubes},
      correspondence_address1={Wagner, C.; Technische Universität Chemnitz, Reichenhainer Straße 70, Germany; email: christian.wagner@zfm.tu-chemnitz.de},
      publisher={American Physical Society},
      issn={24699950},
      language={English},
      abbrev_source_title={Phys. Rev. B},
      document_type={Article},
      source={Scopus},
      }

  • Copolymers of Diketopyrrolopyrrole and Benzothiadiazole: Design and Function from Simulations with Experimental Support
    • D. Raychev, R. D. Méndez López, A. Kiriy, G. Seifert, J. -U. Sommer, O. Guskova
    • Macromolecules 52, 904-914 (2019)
    • DOI   Abstract  

      Alternating block copolymers consisting of diketopyrrolopyrrole and benzothiadiazole electron acceptor units linked together via aromatic five-membered donor heterocycles are studied using a combination of computer simulation techniques and experiments. Four copolymers are modeled starting from their monomers to stacked macromolecules: with two different linkers – thiophene or furan, connecting electron-withdrawing core units – and two different alkyl substituents at lactam nitrogens of diketopyrrolopyrrole – linear dodecyl and branched 2-octyldodecyl chains. In our experiments, we aim at characterization of the optical and electrochemical properties of two copolymers with branched side chains differing in the linker, since as the literature survey shows the data published on these copolymers are very sparse. These properties can be easily interpreted and later compared with theoretical predictions. The results of simulations supported by experiments show that monomers of these polymers have very similar electronic and optical properties, and the main difference between them consists in various chain curvature defined by the linker. More curved furan-containing monomers and more stretched thiophene-linked molecules are characterized by different energetics of the stack formation and diverse in charge carrier mobilities. The branching of the side chains affects the planarity of the macromolecules, leads to longer π- π stacking distance and lamellar interval in the ordered arrays of polymers, and defines the stacking patterns of the conjugated backbones. The ambipolar transport is predicted for the majority of considered copolymer morphologies, and a quantitatively satisfactory agreement between experiment and computation is achieved. © 2019 American Chemical Society.

      @ARTICLE{Raychev2019904,
      author={Raychev, D. and Méndez López, R.D. and Kiriy, A. and Seifert, G. and Sommer, J.-U. and Guskova, O.},
      title={Copolymers of Diketopyrrolopyrrole and Benzothiadiazole: Design and Function from Simulations with Experimental Support},
      journal={Macromolecules},
      year={2019},
      volume={52},
      number={3},
      pages={904-914},
      doi={10.1021/acs.macromol.8b02500},
      note={cited By 6},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061632151&doi=10.1021%2facs.macromol.8b02500&partnerID=40&md5=79c4cd9b38eb63bba050ac0d1d1fc054},
      affiliation={Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Institute of Macromolecular Chemistry, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Theoretical Chemistry, Technische Universität Dresden, Dresden, 01062, Germany; Institute of Theoretical Physics, Technische Universität Dresden, Zellescher Weg 17, Dresden, 01069, Germany},
      abstract={Alternating block copolymers consisting of diketopyrrolopyrrole and benzothiadiazole electron acceptor units linked together via aromatic five-membered donor heterocycles are studied using a combination of computer simulation techniques and experiments. Four copolymers are modeled starting from their monomers to stacked macromolecules: with two different linkers - thiophene or furan, connecting electron-withdrawing core units - and two different alkyl substituents at lactam nitrogens of diketopyrrolopyrrole - linear dodecyl and branched 2-octyldodecyl chains. In our experiments, we aim at characterization of the optical and electrochemical properties of two copolymers with branched side chains differing in the linker, since as the literature survey shows the data published on these copolymers are very sparse. These properties can be easily interpreted and later compared with theoretical predictions. The results of simulations supported by experiments show that monomers of these polymers have very similar electronic and optical properties, and the main difference between them consists in various chain curvature defined by the linker. More curved furan-containing monomers and more stretched thiophene-linked molecules are characterized by different energetics of the stack formation and diverse in charge carrier mobilities. The branching of the side chains affects the planarity of the macromolecules, leads to longer π- π stacking distance and lamellar interval in the ordered arrays of polymers, and defines the stacking patterns of the conjugated backbones. The ambipolar transport is predicted for the majority of considered copolymer morphologies, and a quantitatively satisfactory agreement between experiment and computation is achieved. © 2019 American Chemical Society.},
      keywords={Block copolymers; Carrier mobility; Conjugated polymers; Macromolecules; Monomers; Organic pollutants; Thiophene, Ambipolar transport; Benzothiadiazoles; Branched side chains; Conjugated backbones; Diketopyrrolopyrroles; Electronic and optical properties; Electronwithdrawing; Simulation technique, Optical properties},
      correspondence_address1={Guskova, O.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: guskova@ipfdd.de},
      publisher={American Chemical Society},
      issn={00249297},
      coden={MAMOB},
      language={English},
      abbrev_source_title={Macromolecules},
      document_type={Article},
      source={Scopus},
      }

  • A review of numerical models for 3D woven composite reinforcements
    • T. Gereke, C. Cherif
    • Composite Structures 209, 60-66 (2019)
    • DOI   Abstract  

      In recent years, a new class of composite reinforcements has gained considerable attention: 3D woven fabrics. Their advantages in terms of reducing preforming steps and their resistance to impact and delamination have been clearly proven. However, relationships between fabric structure and composite properties are still largely unknown. Numerical models on different length scales were developed that capture the mechanical behavior of fabrics and their composites. This paper reviews models for 3D woven fabrics in the dry state and discusses results that were achieved with parametric studies. Special attention is given to the determination of the initial configuration of the 3D woven fabric model. The multi-filament character of yarns is best depicted with meso-scale approaches that describe the sub-yarn behavior with realistic models. Developed models can be used for further investigations, e. g. the optimization of fabric structure and forming processes. © 2018 Elsevier Ltd

      @ARTICLE{Gereke201960,
      author={Gereke, T. and Cherif, C.},
      title={A review of numerical models for 3D woven composite reinforcements},
      journal={Composite Structures},
      year={2019},
      volume={209},
      pages={60-66},
      doi={10.1016/j.compstruct.2018.10.085},
      note={cited By 60},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055735283&doi=10.1016%2fj.compstruct.2018.10.085&partnerID=40&md5=32f17c8aa9512e2b85a37525209f21e9},
      affiliation={Technische Universität Dresden, Institute of Textile Machinery and High Performance Material Technology and Dresden Center for Computational Materials Science (DCMS), Dresden, 01062, Germany},
      abstract={In recent years, a new class of composite reinforcements has gained considerable attention: 3D woven fabrics. Their advantages in terms of reducing preforming steps and their resistance to impact and delamination have been clearly proven. However, relationships between fabric structure and composite properties are still largely unknown. Numerical models on different length scales were developed that capture the mechanical behavior of fabrics and their composites. This paper reviews models for 3D woven fabrics in the dry state and discusses results that were achieved with parametric studies. Special attention is given to the determination of the initial configuration of the 3D woven fabric model. The multi-filament character of yarns is best depicted with meso-scale approaches that describe the sub-yarn behavior with realistic models. Developed models can be used for further investigations, e. g. the optimization of fabric structure and forming processes. © 2018 Elsevier Ltd},
      author_keywords={3D woven fabrics; Mechanical properties; Numerical analysis; Textiles},
      keywords={Fabrics; Mechanical properties; Numerical analysis; Numerical models; Reinforcement; Structural optimization; Textiles; Yarn, 3D woven composites; 3d woven fabrics; Composite properties; Composite reinforcement; Different length scale; Fabric structures; Initial configuration; Mechanical behavior, Weaving},
      correspondence_address1={Gereke, T.; Technische Universität Dresden, Germany; email: thomas.gereke@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={02638223},
      coden={COMSE},
      language={English},
      abbrev_source_title={Compos. Struct.},
      document_type={Review},
      source={Scopus},
      }

  • Effects of external mechanical or magnetic fields and defects on electronic and transport properties of graphene
    • T. M. Radchenko, V. A. Tatarenko, G. Cuniberti
    • Materials Today: Proceedings 35, 523-529 (2019)
    • DOI   Abstract  

      We report on the results obtained modelling the electronic and transport properties of single-layer graphene subjected to mechanical or magnetic fields and containing point defects. Reviewing, analyzing, and generalizing our findings, we claim that effects of uniaxial tensile strain or shear deformation along with their combination as well as structural imperfections (defects) can be useful for achieving the new level of functionalization of graphene, viz. for tailoring its electrotransport properties via tuning its band gap value as much as it is enough to achieve the graphene transformation from the zero-band-gap semimetal into the semiconductor and even reach the gap values that are substantially higher than for some materials (including silicon) typically used in nanoelectronic devices. © 2019 Elsevier Ltd.

      @ARTICLE{Radchenko2019523,
      author={Radchenko, T.M. and Tatarenko, V.A. and Cuniberti, G.},
      title={Effects of external mechanical or magnetic fields and defects on electronic and transport properties of graphene},
      journal={Materials Today: Proceedings},
      year={2019},
      volume={35},
      pages={523-529},
      doi={10.1016/j.matpr.2019.10.014},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85101011575&doi=10.1016%2fj.matpr.2019.10.014&partnerID=40&md5=825bd19f302a6970d4d087ada5c08790},
      affiliation={G.V. Kurdyumov Institute for Metal Physics of the NAS of Ukraine, Kyiv, 03142, Ukraine; Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany},
      abstract={We report on the results obtained modelling the electronic and transport properties of single-layer graphene subjected to mechanical or magnetic fields and containing point defects. Reviewing, analyzing, and generalizing our findings, we claim that effects of uniaxial tensile strain or shear deformation along with their combination as well as structural imperfections (defects) can be useful for achieving the new level of functionalization of graphene, viz. for tailoring its electrotransport properties via tuning its band gap value as much as it is enough to achieve the graphene transformation from the zero-band-gap semimetal into the semiconductor and even reach the gap values that are substantially higher than for some materials (including silicon) typically used in nanoelectronic devices. © 2019 Elsevier Ltd.},
      author_keywords={Band gap; Defects; Graphene; Magnetic field; Strain},
      keywords={Graphene; Magnetic field effects; Point defects; Semiconductor devices; Shear flow; Tensile strain; Transport properties, Electrotransport; Functionalizations; Magnetic defects; Magnetic-field; Mechanical field; Property; Single layer; Structural imperfections; Tensile shears; Uniaxial tensile strain, Energy gap},
      correspondence_address1={Radchenko, T.M.; G.V. Kurdyumov Institute for Metal Physics of the NAS of UkraineUkraine; email: tarad@imp.kiev.ua},
      editor={Prokopiv V., Litovchenko V., Nykyruy L., Turovska L., Strikha M.},
      publisher={Elsevier Ltd},
      issn={22147853},
      language={English},
      abbrev_source_title={Mater. Today Proc.},
      document_type={Conference Paper},
      source={Scopus},
      }

  • A zinc selective oxytocin based biosensor
    • E. Mervinetsky, I. Alshanski, K. K. Tadi, M. Hurevich, S. Yitzchaik, A. Dianat, J. Buchwald, R. Gutierrez, G. Cuniberti
    • Journal of Materials Chemistry B 8, 155-160 (2019)
    • DOI   Abstract  

      Oxytocin is a peptide hormone with high affinity to both Zn2+ and Cu2+ ions compared to other metal ions. This affinity makes oxytocin an attractive recognition layer for monitoring the levels of these essential ions in biofluids. Native oxytocin cannot differentiate between Cu2+ and Zn2+ ions and hence it is not useful for sensing Zn2+ in the presence of Cu2+. We elucidated the effect of the terminal amine group of oxytocin on the affinity toward Cu2+ using theoretical calculations. We designed a new Zn2+ selective oxytocin-based biosensor that utilizes the terminal amine for surface anchoring, also preventing the response to Cu2+. The biosensor shows exceptional selectivity and very high sensitivity to Zn2+ in impedimetric biosensing. This study shows for the first time an oxytocin derived sensor that can be used directly for sensing Zn2+ in the presence of Cu2+ This journal is © The Royal Society of Chemistry.

      @ARTICLE{Mervinetsky2019155,
      author={Mervinetsky, E. and Alshanski, I. and Tadi, K.K. and Hurevich, M. and Yitzchaik, S. and Dianat, A. and Buchwald, J. and Gutierrez, R. and Cuniberti, G.},
      title={A zinc selective oxytocin based biosensor},
      journal={Journal of Materials Chemistry B},
      year={2019},
      volume={8},
      number={1},
      pages={155-160},
      doi={10.1039/c9tb01932d},
      note={cited By 6},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85076876611&doi=10.1039%2fc9tb01932d&partnerID=40&md5=d2f741c7c8c39940b277c5add88bf1ec},
      affiliation={Institute of Chemistry and the Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, 91904, Israel; Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={Oxytocin is a peptide hormone with high affinity to both Zn2+ and Cu2+ ions compared to other metal ions. This affinity makes oxytocin an attractive recognition layer for monitoring the levels of these essential ions in biofluids. Native oxytocin cannot differentiate between Cu2+ and Zn2+ ions and hence it is not useful for sensing Zn2+ in the presence of Cu2+. We elucidated the effect of the terminal amine group of oxytocin on the affinity toward Cu2+ using theoretical calculations. We designed a new Zn2+ selective oxytocin-based biosensor that utilizes the terminal amine for surface anchoring, also preventing the response to Cu2+. The biosensor shows exceptional selectivity and very high sensitivity to Zn2+ in impedimetric biosensing. This study shows for the first time an oxytocin derived sensor that can be used directly for sensing Zn2+ in the presence of Cu2+ This journal is © The Royal Society of Chemistry.},
      keywords={Body fluids; Metal ions; Metals; Peptides; Zinc, Amine groups; Biosensing; High affinity; High sensitivity; Peptide hormones; Recognition layer; Surface-anchoring; Theoretical calculations, Biosensors, gold; oxytocin; protein binding; thioctic acid; zinc, chemistry; genetic procedures; metabolism, Biosensing Techniques; Gold; Oxytocin; Protein Binding; Thioctic Acid; Zinc},
      correspondence_address1={Gutierrez, R.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: rafael.gutierrez@tu-dresden.de},
      publisher={Royal Society of Chemistry},
      issn={2050750X},
      coden={JMCBD},
      pubmed_id={31782469},
      language={English},
      abbrev_source_title={J. Mater. Chem. B},
      document_type={Article},
      source={Scopus},
      }

  • Swelling and shrinking in prestressed polymer gels: An incremental stress-diffusion analysis
    • M. Rossi, P. Nardinocchi, T. Wallmersperger
    • Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, 20190174 (2019)
    • DOI   Abstract  

      Polymer gels are porous fluid-saturated materials which can swell or shrink triggered by various stimuli. The swelling/shrinking-induced deformation can generate large stresses which may lead to the failure of the material. In the present research, a nonlinear stress-diffusion model is employed to investigate the stress and the deformation state arising in hydrated constrained polymer gels when subject to a varying chemical potential. Two different constraint configurations are taken into account: (i) elastic constraint along the thickness direction and (ii) plane elastic constraint. The first step entirely defines a compressed/tensed configuration. From there, an incremental chemo-mechanical analysis is presented. The derived model extends the classical linear poroelastic theory with respect to a prestressed configuration. Finally, the comparison between the analytical results obtained by the proposed model and a particular problem already discussed in literature for a stress-free gelmembrane (one-dimensional test case) will highlight the relevance of the derived model. © 2019 The Author(s) Published by the Royal Society. All rights reserved.

      @ARTICLE{Rossi2019,
      author={Rossi, M. and Nardinocchi, P. and Wallmersperger, T.},
      title={Swelling and shrinking in prestressed polymer gels: An incremental stress-diffusion analysis},
      journal={Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences},
      year={2019},
      volume={475},
      number={2230},
      doi={10.1098/rspa.2019.0174},
      art_number={20190174},
      note={cited By 5},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074779553&doi=10.1098%2frspa.2019.0174&partnerID=40&md5=a7803b3a96e0acae185412bb69476530},
      affiliation={Institute of Solid Mechanics, TU Dresden, George-Bähr-Straße 3c, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Hallwachsstraße 3, Dresden, 01069, Germany; Department of Structural and Geotechnical Engineering, Sapienza Università di Roma, via Eudossiana 18, Roma, 00184, Italy},
      abstract={Polymer gels are porous fluid-saturated materials which can swell or shrink triggered by various stimuli. The swelling/shrinking-induced deformation can generate large stresses which may lead to the failure of the material. In the present research, a nonlinear stress-diffusion model is employed to investigate the stress and the deformation state arising in hydrated constrained polymer gels when subject to a varying chemical potential. Two different constraint configurations are taken into account: (i) elastic constraint along the thickness direction and (ii) plane elastic constraint. The first step entirely defines a compressed/tensed configuration. From there, an incremental chemo-mechanical analysis is presented. The derived model extends the classical linear poroelastic theory with respect to a prestressed configuration. Finally, the comparison between the analytical results obtained by the proposed model and a particular problem already discussed in literature for a stress-free gelmembrane (one-dimensional test case) will highlight the relevance of the derived model. © 2019 The Author(s) Published by the Royal Society. All rights reserved.},
      author_keywords={Active materials; Incremental analysis; Polymer gels; Prestressed state; Stress-diffusion theory; Swelling/shrinking},
      keywords={Chemical analysis; Deformation; Diffusion; Polymers; Prestressed materials; Swelling, Active material; Incremental analysis; Polymer gels; Pre-stressed; Stress diffusion, Gels},
      correspondence_address1={Rossi, M.; Institute of Solid Mechanics, George-Bähr-Straße 3c, Germany; email: marco.rossi@tu-dresden.de},
      publisher={Royal Society Publishing},
      issn={13645021},
      language={English},
      abbrev_source_title={Proc. R. Soc. A Math. Phys. Eng. Sci.},
      document_type={Article},
      source={Scopus},
      }

  • Stabilization of aqueous graphene dispersions utilizing a biocompatible dispersant: a molecular dynamics study
    • S. Huang, A. Croy, V. Bezugly, G. Cuniberti
    • Physical Chemistry Chemical Physics 21, 24007-24016 (2019)
    • DOI   Abstract  

      Flavin mononucleotide sodium (FMNS) was recently reported as a highly efficient dispersant for the exfoliation of defect-free, few-layer, stabilized aqueous graphene dispersions. Most importantly, FMNS is innocuous and eco-friendly and can facilitate biomedical applications of graphene. Complementing those experimental studies, the influence of FMNS molecules on the aggregation behavior of graphene flakes in solution is investigated via all-atom molecular dynamics simulations. The stabilizing role of FMNS is demonstrated by the potential of mean force calculations for pairs of graphene flakes covered by FMNS molecules. These results indicate that the optimal amount ratio between FMNS molecules and carbon atoms in monolayer graphene is about 0.026 leading to a surface coverage of 0.34 FMNS molecules per nm2 on the graphene flakes. Overall the simulations support the high efficiency of FMNS as a surfactant compared to other surfactants. © 2019 the Owner Societies.

      @ARTICLE{Huang201924007,
      author={Huang, S. and Croy, A. and Bezugly, V. and Cuniberti, G.},
      title={Stabilization of aqueous graphene dispersions utilizing a biocompatible dispersant: a molecular dynamics study},
      journal={Physical Chemistry Chemical Physics},
      year={2019},
      volume={21},
      number={43},
      pages={24007-24016},
      doi={10.1039/c9cp04742e},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85074674949&doi=10.1039%2fc9cp04742e&partnerID=40&md5=32e8e76766cf36484b517b0fa7535452},
      affiliation={Institute for Materials Science and Max Bergmann Center for Biomaterials, Technische Universität Dresden, Dresden, 01062, Germany; Life Science Inkubator Sachsen GmbH and Co. KG, Tatzberg 47, Dresden, 01307, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={Flavin mononucleotide sodium (FMNS) was recently reported as a highly efficient dispersant for the exfoliation of defect-free, few-layer, stabilized aqueous graphene dispersions. Most importantly, FMNS is innocuous and eco-friendly and can facilitate biomedical applications of graphene. Complementing those experimental studies, the influence of FMNS molecules on the aggregation behavior of graphene flakes in solution is investigated via all-atom molecular dynamics simulations. The stabilizing role of FMNS is demonstrated by the potential of mean force calculations for pairs of graphene flakes covered by FMNS molecules. These results indicate that the optimal amount ratio between FMNS molecules and carbon atoms in monolayer graphene is about 0.026 leading to a surface coverage of 0.34 FMNS molecules per nm2 on the graphene flakes. Overall the simulations support the high efficiency of FMNS as a surfactant compared to other surfactants. © 2019 the Owner Societies.},
      keywords={Biocompatibility; Dispersions; Medical applications; Molecular dynamics; Molecules; Surface active agents, Aggregation behavior; Biomedical applications; Flavin mononucleotides; Graphene dispersions; High-efficiency; Molecular dynamics simulations; Potential of mean force; Surface coverages, Graphene},
      correspondence_address1={Croy, A.; Institute for Materials Science and Max Bergmann Center for Biomaterials, Germany; email: alexander.croy@tu-dresden.de},
      publisher={Royal Society of Chemistry},
      issn={14639076},
      coden={PPCPF},
      pubmed_id={31646309},
      language={English},
      abbrev_source_title={Phys. Chem. Chem. Phys.},
      document_type={Article},
      source={Scopus},
      }

  • Top dielectric induced ambipolarity in an n-channel dual-gated organic field effect transistor
    • K. Bairagi, E. Zuccatti, F. Calavalle, S. Catalano, S. Parui, R. Llopis, F. Ortmann, F. Casanova, L. E. Hueso
    • Journal of Materials Chemistry C 7, 10389-10393 (2019)
    • DOI   Abstract  

      The realization of both p-type and n-type operations in a single organic field effect transistor (OFET) is critical for simplifying the design of complex organic circuits. Typically, only p-type or n-type operation is realized in an OFET, while the respective counterpart is either suppressed by charge trapping or limited by the injection barrier with the electrodes. Here we show that only the presence of a top dielectric turns an n-type polymer semiconductor (N2200, Polyera ActiveInk™) into an ambipolar one, as detected from both bottom and top gated OFET operation. The effect is independent of the channel thickness and the top dielectric combinations. Variable temperature transfer characteristics show that both the electrons and holes can be equally transported through the bulk of the polymer semiconductor. © 2019 The Royal Society of Chemistry.

      @ARTICLE{Bairagi201910389,
      author={Bairagi, K. and Zuccatti, E. and Calavalle, F. and Catalano, S. and Parui, S. and Llopis, R. and Ortmann, F. and Casanova, F. and Hueso, L.E.},
      title={Top dielectric induced ambipolarity in an n-channel dual-gated organic field effect transistor},
      journal={Journal of Materials Chemistry C},
      year={2019},
      volume={7},
      number={33},
      pages={10389-10393},
      doi={10.1039/c9tc02912e},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071262778&doi=10.1039%2fc9tc02912e&partnerID=40&md5=fc97561394d7b09ff29de5c589b3e61a},
      affiliation={CIC NanoGUNE, San Sebastian, 20018, Spain; Center for Advancing Electronics Dresden, Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain; IMEC, K. U. Leuven, Leuven, 3001, Belgium},
      abstract={The realization of both p-type and n-type operations in a single organic field effect transistor (OFET) is critical for simplifying the design of complex organic circuits. Typically, only p-type or n-type operation is realized in an OFET, while the respective counterpart is either suppressed by charge trapping or limited by the injection barrier with the electrodes. Here we show that only the presence of a top dielectric turns an n-type polymer semiconductor (N2200, Polyera ActiveInk™) into an ambipolar one, as detected from both bottom and top gated OFET operation. The effect is independent of the channel thickness and the top dielectric combinations. Variable temperature transfer characteristics show that both the electrons and holes can be equally transported through the bulk of the polymer semiconductor. © 2019 The Royal Society of Chemistry.},
      keywords={Charge trapping; Transistors, Channel thickness; Electrons and holes; Injection barriers; N-type polymers; Organic circuits; Polymer semiconductors; Transfer characteristics; Variable temperature, Organic field effect transistors},
      correspondence_address1={Bairagi, K.; CIC NanoGUNESpain; email: k.bairagi@nanogune.eu},
      publisher={Royal Society of Chemistry},
      issn={20507534},
      coden={JMCCC},
      language={English},
      abbrev_source_title={J. Mater. Chem. C},
      document_type={Article},
      source={Scopus},
      }

  • Quantum phonon transport in nanomaterials: Combining atomistic with non-equilibrium green’s function techniques
    • L. M. Sandonas, R. Gutierrez, A. Pecchia, A. Croy, G. Cuniberti
    • Entropy 21, 735 (2019)
    • DOI   Abstract  

      A crucial goal for increasing thermal energy harvesting will be to progress towards atomistic design strategies for smart nanodevices and nanomaterials. This requires the combination of computationally efficient atomisticmethodologies with quantum transport based approaches. Here, we review our recent work on this problem, by presenting selected applications of the PHONON tool to the description of phonon transport in nanostructured materials. The PHONON tool is a module developed as part of the Density-Functional Tight-Binding (DFTB) software platform. We discuss the anisotropic phonon band structure of selected puckered two-dimensional materials, helical and horizontal doping effects in the phonon thermal conductivity of boron nitride-carbon heteronanotubes, phonon filtering in molecular junctions, and a novel computational methodology to investigate time-dependent phonon transport at the atomistic level. These examples illustrate the versatility of our implementation of phonon transport in combination with density functional-based methods to address specific nanoscale functionalities, thus potentially allowing for designing novel thermal devices. © 2019 by the authors.

      @ARTICLE{Sandonas2019,
      author={Sandonas, L.M. and Gutierrez, R. and Pecchia, A. and Croy, A. and Cuniberti, G.},
      title={Quantum phonon transport in nanomaterials: Combining atomistic with non-equilibrium green's function techniques},
      journal={Entropy},
      year={2019},
      volume={21},
      number={8},
      doi={10.3390/e21080735},
      art_number={735},
      note={cited By 7},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070463687&doi=10.3390%2fe21080735&partnerID=40&md5=ea579f4728abb94d0e8fbce5e09036ac},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Consiglio Nazionale delle Ricerche, ISMN, Via Salaria km 29.6, Monterotondo, Rome, 00017, Italy; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Physics and Materials Science Research Unit, University of LuxembourgL-1511, Luxembourg},
      abstract={A crucial goal for increasing thermal energy harvesting will be to progress towards atomistic design strategies for smart nanodevices and nanomaterials. This requires the combination of computationally efficient atomisticmethodologies with quantum transport based approaches. Here, we review our recent work on this problem, by presenting selected applications of the PHONON tool to the description of phonon transport in nanostructured materials. The PHONON tool is a module developed as part of the Density-Functional Tight-Binding (DFTB) software platform. We discuss the anisotropic phonon band structure of selected puckered two-dimensional materials, helical and horizontal doping effects in the phonon thermal conductivity of boron nitride-carbon heteronanotubes, phonon filtering in molecular junctions, and a novel computational methodology to investigate time-dependent phonon transport at the atomistic level. These examples illustrate the versatility of our implementation of phonon transport in combination with density functional-based methods to address specific nanoscale functionalities, thus potentially allowing for designing novel thermal devices. © 2019 by the authors.},
      author_keywords={Density-functional tight binding; Green's functions; Landauer approach; Nanostructured materials; Phonon transport; Time-dependent transport},
      correspondence_address1={Cuniberti, G.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: gianaurelio.cuniberti@tu-dresden.de},
      publisher={MDPI AG},
      issn={10994300},
      language={English},
      abbrev_source_title={Entropy},
      document_type={Review},
      source={Scopus},
      }

  • On-surface synthesis of nitrogen-doped nanographenes with 5-7 membered rings
    • D. Skidin, F. Eisenhut, M. Richter, S. Nikipar, J. Krüger, D. A. Ryndyk, R. Berger, G. Cuniberti, X. Feng, F. Moresco
    • Chemical Communications 55, 4731-4734 (2019)
    • DOI   Abstract  

      We report on the formation of nitrogen-doped nanographenes containing five- and seven-membered rings by thermally induced cyclodehydrogenation on the Au(111) surface. Using scanning tunneling microscopy and supported by calculations, we investigated the structure of the precursor and targets, as well as of intermediates. Scanning tunneling spectroscopy shows that the electronic properties of the target nanographenes are strongly influenced by the additional formation of non-hexagonal rings. © The Royal Society of Chemistry.

      @ARTICLE{Skidin20194731,
      author={Skidin, D. and Eisenhut, F. and Richter, M. and Nikipar, S. and Krüger, J. and Ryndyk, D.A. and Berger, R. and Cuniberti, G. and Feng, X. and Moresco, F.},
      title={On-surface synthesis of nitrogen-doped nanographenes with 5-7 membered rings},
      journal={Chemical Communications},
      year={2019},
      volume={55},
      number={32},
      pages={4731-4734},
      doi={10.1039/C9CC00276F},
      note={cited By 11},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85064551398&doi=10.1039%2fC9CC00276F&partnerID=40&md5=14818b683d511b38717d8d1f92d8ae85},
      affiliation={Institute for Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Institute of Molecular Functional Materials, Department of Chemistry and Food Chemistry, TU Dresden, Dresden, 01062, Germany; Bremen Center for Computational Materials Science, Department of Physics, Universität Bremen, Bremen, 28359, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={We report on the formation of nitrogen-doped nanographenes containing five- and seven-membered rings by thermally induced cyclodehydrogenation on the Au(111) surface. Using scanning tunneling microscopy and supported by calculations, we investigated the structure of the precursor and targets, as well as of intermediates. Scanning tunneling spectroscopy shows that the electronic properties of the target nanographenes are strongly influenced by the additional formation of non-hexagonal rings. © The Royal Society of Chemistry.},
      keywords={benzoisoindole; gold; graphene; isoindole derivative; nitrogen; unclassified drug, Article; chemical structure; dehydrogenation; low temperature; molecule; scanning tunneling microscopy; scanning tunneling spectroscopy; synthesis},
      correspondence_address1={Moresco, F.; Center for Advancing Electronics Dresden, Germany; email: francesca.moresco@tu-dresden.de},
      publisher={Royal Society of Chemistry},
      issn={13597345},
      coden={CHCOF},
      pubmed_id={30942792},
      language={English},
      abbrev_source_title={Chem. Commun.},
      document_type={Article},
      source={Scopus},
      }

  • Immobilization of detonation nanodiamonds on macroscopic surfaces
    • S. Balakin, N. R. Dennison, B. Klemmed, J. Spohn, G. Cuniberti, L. Römhildt, J. Opitz
    • Applied Sciences (Switzerland) 9, 1064 (2019)
    • DOI   Abstract  

      Detonation nanodiamonds (NDs) are a novel class of carbon-based nanomaterials, and have received a great deal of attention in biomedical applications, due to their high biocompatibility, facile surface functionalization, and commercialized synthetic fabrication. We were able to transfer the NDs from large-size agglomerate suspensions to homogenous coatings. ND suspensions have been used in various techniques to coat on commercially available substrates of pure Ti and Si. Scanning electron microscopy (SEM) imaging and nanoindentation show that the densest and strongest coating of NDs was generated when using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide (EDC/NHS)-mediated coupling to macroscopic silanized surfaces. In the next step, the feasibility of DNA-mediated coupling of NDs on macroscopic surfaces is discussed using fluorescent microscopy and additional particle size distribution, as well as zeta potential measurements. This work compares different ND coating strategies and describes the straightforward technique of grafting single-stranded DNA onto carboxylated NDs via thioester bridges. © 2019 by the authors.

      @ARTICLE{Balakin2019,
      author={Balakin, S. and Dennison, N.R. and Klemmed, B. and Spohn, J. and Cuniberti, G. and Römhildt, L. and Opitz, J.},
      title={Immobilization of detonation nanodiamonds on macroscopic surfaces},
      journal={Applied Sciences (Switzerland)},
      year={2019},
      volume={9},
      number={6},
      doi={10.3390/app9061064},
      art_number={1064},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063737220&doi=10.3390%2fapp9061064&partnerID=40&md5=7baca2592ae003af2ba9b3ae6fa9852d},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01062, Germany; Fraunhofer Institute for Ceramic Technologies and Systems IKTS Material Diagnostics, Dresden, 01109, Germany; Physical Chemistry, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01062, Germany; Fraunhofer Institute for Ceramic Technologies and Systems IKTS Material Diagnostics, Leipzig, 04103, Germany},
      abstract={Detonation nanodiamonds (NDs) are a novel class of carbon-based nanomaterials, and have received a great deal of attention in biomedical applications, due to their high biocompatibility, facile surface functionalization, and commercialized synthetic fabrication. We were able to transfer the NDs from large-size agglomerate suspensions to homogenous coatings. ND suspensions have been used in various techniques to coat on commercially available substrates of pure Ti and Si. Scanning electron microscopy (SEM) imaging and nanoindentation show that the densest and strongest coating of NDs was generated when using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide (EDC/NHS)-mediated coupling to macroscopic silanized surfaces. In the next step, the feasibility of DNA-mediated coupling of NDs on macroscopic surfaces is discussed using fluorescent microscopy and additional particle size distribution, as well as zeta potential measurements. This work compares different ND coating strategies and describes the straightforward technique of grafting single-stranded DNA onto carboxylated NDs via thioester bridges. © 2019 by the authors.},
      author_keywords={Bio-conjugation; De-agglomeration; Detonation nanodiamonds; Fluorescent microscopy; Nanoindentation},
      correspondence_address1={Opitz, J.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: Joerg.opitz@ikts.fraunhofer.de},
      publisher={MDPI AG},
      issn={20763417},
      language={English},
      abbrev_source_title={Appl. Sci.},
      document_type={Article},
      source={Scopus},
      }

  • Modeling of the coadsorption of chloride and hydrogen ions on copper electrode surface
    • H. Yang, A. Dianat, M. Bobeth, G. Cuniberti
    • Journal of the Electrochemical Society 166, D3042-D3048 (2019)
    • DOI   Abstract  

      For manufacturing copper interconnects by the damscence technique, electrochemical deposition of copper on patterned sustrates requires several additives to achieve compact filling of trenches and vias, where chloride ions play a crucial role. In the highly acidic electrolyte, adsorption of chloride ions on copper is expected to compete with the adsorption of hydrogen, depending on the copper electrode potential. We propose a general phenomenological model of the coadsorption of two ion species which is supported by DFT calculations and show how the adsorption of one species can be described by the common Langmuir model with rescaled parameters depending on the concentration of the second species. Regarding the Cl–H+-system, corresponding model parameters are estimated by fitting radio tracer measurements of the chloride adsorption on copper reported in the literature. The data suggest that in a highly acidic solution (pH ≈ 0) the saturation surface density of chloride depends strongly on the electrode potential. With variation of the potential ESHE from -0.4 to +0.2 V, the saturation density changes by a factor of four. Within our model, such a potential dependence of the saturation density is explained by the presence of adsorbed hydrogen. © The Author(s) 2018. Published by ECS.

      @ARTICLE{Yang2019D3042,
      author={Yang, H. and Dianat, A. and Bobeth, M. and Cuniberti, G.},
      title={Modeling of the coadsorption of chloride and hydrogen ions on copper electrode surface},
      journal={Journal of the Electrochemical Society},
      year={2019},
      volume={166},
      number={1},
      pages={D3042-D3048},
      doi={10.1149/2.0061901jes},
      note={cited By 1},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85063081413&doi=10.1149%2f2.0061901jes&partnerID=40&md5=1255c868c7b862de62bfe9d9b7fe591f},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCCMS), TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden (CfAED), Dresden, 01069, Germany},
      abstract={For manufacturing copper interconnects by the damscence technique, electrochemical deposition of copper on patterned sustrates requires several additives to achieve compact filling of trenches and vias, where chloride ions play a crucial role. In the highly acidic electrolyte, adsorption of chloride ions on copper is expected to compete with the adsorption of hydrogen, depending on the copper electrode potential. We propose a general phenomenological model of the coadsorption of two ion species which is supported by DFT calculations and show how the adsorption of one species can be described by the common Langmuir model with rescaled parameters depending on the concentration of the second species. Regarding the Cl--H+-system, corresponding model parameters are estimated by fitting radio tracer measurements of the chloride adsorption on copper reported in the literature. The data suggest that in a highly acidic solution (pH ≈ 0) the saturation surface density of chloride depends strongly on the electrode potential. With variation of the potential ESHE from -0.4 to +0.2 V, the saturation density changes by a factor of four. Within our model, such a potential dependence of the saturation density is explained by the presence of adsorbed hydrogen. © The Author(s) 2018. Published by ECS.},
      keywords={Additives; Chlorine compounds; Copper; Electrochemical deposition; Electrodes; Electrolytes; Gas adsorption; Ions; Reduction, Acidic electrolytes; Chloride adsorption; Copper interconnects; Electrode potentials; Phenomenological modeling; Potential dependence; Saturation density; Tracer measurement, Integrated circuit interconnects},
      publisher={Electrochemical Society Inc.},
      issn={00134651},
      coden={JESOA},
      language={English},
      abbrev_source_title={J Electrochem Soc},
      document_type={Article},
      source={Scopus},
      }

  • Engineering Kitaev exchange in stacked iridate layers: Impact of inter-layer species on in-plane magnetism
    • R. Yadav, M. S. Eldeeb, R. Ray, S. Aswartham, M. I. Sturza, S. Nishimoto, J. Van Den Brink, L. Hozoi
    • Chemical Science 10, 1866-1872 (2019)
    • DOI   Abstract  

      Novel functionalities may be achieved in oxide electronics by appropriate stacking of planar oxide layers of different metallic species, MOp and M′Oq. The simplest mechanism allowing the tailoring of the electronic states and physical properties of such heterostructures is of electrostatic nature – charge imbalance between the M and M′ cations. Here we clarify the effect of interlayer electrostatics on the anisotropic Kitaev exchange in H3LiIr2O6, a recently proposed realization of the Kitaev spin liquid. By quantum chemical calculations, we show that the precise position of H+ cations between magnetically active [LiIr2O6]3- honeycomb-like layers has a strong impact on the magnitude of Kitaev interactions. In particular, it is found that stacking with straight interlayer O-H-O links is detrimental to in-plane Kitaev exchange since coordination by a single H-ion of the O ligand implies an axial Coulomb potential at the O site and unfavorable polarization of the O 2p orbitals mediating the Ir-Ir interactions. Our results therefore provide valuable guidelines for the rational design of Kitaev quantum magnets, indicating unprecedented Kitaev interactions of ≈40 meV if the linear interlayer linkage is removed. © 2019 The Royal Society of Chemistry.

      @ARTICLE{Yadav20191866,
      author={Yadav, R. and Eldeeb, M.S. and Ray, R. and Aswartham, S. and Sturza, M.I. and Nishimoto, S. and Van Den Brink, J. and Hozoi, L.},
      title={Engineering Kitaev exchange in stacked iridate layers: Impact of inter-layer species on in-plane magnetism},
      journal={Chemical Science},
      year={2019},
      volume={10},
      number={6},
      pages={1866-1872},
      doi={10.1039/c8sc03018a},
      note={cited By 8},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061126828&doi=10.1039%2fc8sc03018a&partnerID=40&md5=cfd526f394f02d11c1c5ebc35f182504},
      affiliation={Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstr. 20, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Department of Physics, Technical University Dresden, Helmholtzstr. 10, Dresden, 01069, Germany},
      abstract={Novel functionalities may be achieved in oxide electronics by appropriate stacking of planar oxide layers of different metallic species, MOp and M′Oq. The simplest mechanism allowing the tailoring of the electronic states and physical properties of such heterostructures is of electrostatic nature - charge imbalance between the M and M′ cations. Here we clarify the effect of interlayer electrostatics on the anisotropic Kitaev exchange in H3LiIr2O6, a recently proposed realization of the Kitaev spin liquid. By quantum chemical calculations, we show that the precise position of H+ cations between magnetically active [LiIr2O6]3- honeycomb-like layers has a strong impact on the magnitude of Kitaev interactions. In particular, it is found that stacking with straight interlayer O-H-O links is detrimental to in-plane Kitaev exchange since coordination by a single H-ion of the O ligand implies an axial Coulomb potential at the O site and unfavorable polarization of the O 2p orbitals mediating the Ir-Ir interactions. Our results therefore provide valuable guidelines for the rational design of Kitaev quantum magnets, indicating unprecedented Kitaev interactions of ≈40 meV if the linear interlayer linkage is removed. © 2019 The Royal Society of Chemistry.},
      keywords={Binary alloys; Electric fields; Ion exchange; Positive ions; Quantum chemistry, Charge imbalance; Coulomb potential; Interlayer linkage; Magnetically actives; Metallic species; Oxide electronics; Precise position; Quantum chemical calculations, Iridium alloys},
      correspondence_address1={Yadav, R.; Leibniz Institute for Solid State and Materials Research, Helmholtzstr. 20, Germany; email: r.yadav@ifw-dresden.de},
      publisher={Royal Society of Chemistry},
      issn={20416520},
      coden={CSHCC},
      language={English},
      abbrev_source_title={Chem. Sci.},
      document_type={Article},
      source={Scopus},
      }

  • Doping engineering of thermoelectric transport in BNC heteronanotubes
    • L. Medrano Sandonas, G. Cuba-Supanta, R. Gutierrez, C. V. Landauro, J. Rojas-Tapia, G. Cuniberti
    • Physical Chemistry Chemical Physics 21, 1904-1911 (2019)
    • DOI   Abstract  

      BNC heteronanotubes are promising materials for the design of nanoscale thermoelectric devices. In particular, the structural BN doping pattern can be exploited to control the electrical and thermal transport properties of BNC nanostructures. We here address the thermoelectric transport properties of (6,6)-BNC heteronanotubes with helical and horizontal BN doping patterns. For this, we use a density functional tight-binding method combined with the Green’s function technique. Our results show that the electron transmission is reduced and the electronic bandgap increased as a function of the BN concentration for different doping distribution patterns, so that (6,6)-BNC heteronanotubes become semiconducting with a tunable bandgap. The thermal conductance of helical (6,6)-BNC heteronanotubes, which is dominated by phonons, is weakly dependent on BN concentration in the range of 30-80%. Also, the Seebeck coefficient is enhanced by increasing the concentration of helical BN strips. In particular, helical (6,6)-BNC heteronanotubes with a high BN concentration (>20%) display a larger figure of merit compared to other doping distributions and, for a concentration of 50%, reach values up to 2.3 times and 3.4 times the corresponding values of a CNT at 300 K and 800 K, respectively. Our study yields new insights into the parameters tuning the thermoelectric efficiency and thus provides a starting point for designing thermoelectric devices based on BNC nanostructures. © 2019 the Owner Societies.

      @ARTICLE{MedranoSandonas20191904,
      author={Medrano Sandonas, L. and Cuba-Supanta, G. and Gutierrez, R. and Landauro, C.V. and Rojas-Tapia, J. and Cuniberti, G.},
      title={Doping engineering of thermoelectric transport in BNC heteronanotubes},
      journal={Physical Chemistry Chemical Physics},
      year={2019},
      volume={21},
      number={4},
      pages={1904-1911},
      doi={10.1039/c8cp05592k},
      note={cited By 5},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85060400792&doi=10.1039%2fc8cp05592k&partnerID=40&md5=ac5927a11bf09cc7c42744d6f448fdd0},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Max Planck Institute, Physics of Complex Systems, Dresden, 01187, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Faculty of Physical Sciences, National University of San Marcos, P.O. Box 14-0149, Lima, 14, Peru; Centro de Investigaciones Tecnológicas, Biomédicas y Medioambientales (CIBTM), Bella Vista, Callao, Peru; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={BNC heteronanotubes are promising materials for the design of nanoscale thermoelectric devices. In particular, the structural BN doping pattern can be exploited to control the electrical and thermal transport properties of BNC nanostructures. We here address the thermoelectric transport properties of (6,6)-BNC heteronanotubes with helical and horizontal BN doping patterns. For this, we use a density functional tight-binding method combined with the Green's function technique. Our results show that the electron transmission is reduced and the electronic bandgap increased as a function of the BN concentration for different doping distribution patterns, so that (6,6)-BNC heteronanotubes become semiconducting with a tunable bandgap. The thermal conductance of helical (6,6)-BNC heteronanotubes, which is dominated by phonons, is weakly dependent on BN concentration in the range of 30-80%. Also, the Seebeck coefficient is enhanced by increasing the concentration of helical BN strips. In particular, helical (6,6)-BNC heteronanotubes with a high BN concentration (>20%) display a larger figure of merit compared to other doping distributions and, for a concentration of 50%, reach values up to 2.3 times and 3.4 times the corresponding values of a CNT at 300 K and 800 K, respectively. Our study yields new insights into the parameters tuning the thermoelectric efficiency and thus provides a starting point for designing thermoelectric devices based on BNC nanostructures. © 2019 the Owner Societies.},
      keywords={Energy gap; Nanostructures, Density functional tight binding method; Electron transmission; Green's function technique; Thermal transport properties; Thermoelectric devices; Thermoelectric efficiency; Thermoelectric transport; Thermoelectric transport properties, Transport properties},
      correspondence_address1={Medrano Sandonas, L.; Institute for Materials Science, Germany; email: leonardo.medrano@nano.tu-dresden.de},
      publisher={Royal Society of Chemistry},
      issn={14639076},
      coden={PPCPF},
      pubmed_id={30632565},
      language={English},
      abbrev_source_title={Phys. Chem. Chem. Phys.},
      document_type={Article},
      source={Scopus},
      }

2018

  • First-principles investigation of Ag-, Co-, Cr-, Cu-, Fe-, Mn-, Ni-, Pd- and Rh-hexaaminobenzene 2D metal-organic frameworks
    • B. Mortazavi, M. Shahrokhi, M. Makaremi, G. Cuniberti, T. Rabczuk
    • Materials Today Energy 10, 336-342 (2018)
    • DOI   Abstract  

      Hexaaminobenzene (HAB)-derived two-dimensional metal−organic frameworks (MOFs) (Nature Energy 3(2018), 30–36) have most recently gained remarkable attentions as a novel class of two-dimensional (2D) materials, with outstanding performances for advanced energy storage systems. In the latest experimental advances, Ni-, Co- and Cu-HAB MOFs were synthesized in 2D forms, with high electrical conductivities and capacitances as well. Motivated by these experimental advances, we employed first-principles simulations to explore the mechanical, thermal stability and electronic properties of single-layer Ag-, Co-, Cr-, Cu-, Fe-, Mn-, Ni-, Pd- and Rh-HAB MOFs. Theoretical results reveal that Co-, Cr-, Fe-, Mn-, Ni-, Pd- and Rh-HAB nanosheets exhibit linear elasticity with considerable tensile strengths. Ab-initio molecular dynamics results confirm the high thermal stability of all studied nanomembranes. Co- and Fe-HAB monolayers show metallic behavior with low spin-polarization at the Fermi level. Single-layer Ag-, Cu-, Cr-, and Mn-HAB however yield perfect half-metallic behaviors, thus can be promising candidates for the spintronics. In contrast, Ni-, Pd- and Rh-HAB monolayers exhibit nonmagnetic metallic behavior. The insights provided by this investigation confirm the stability and highlight the outstanding physics of transition metal-HAB nanosheets, which are not only highly attractive for the energy storage systems, but may also serve for other advanced applications, like spintronics. © 2018 Elsevier Ltd

      @ARTICLE{Mortazavi2018336,
      author={Mortazavi, B. and Shahrokhi, M. and Makaremi, M. and Cuniberti, G. and Rabczuk, T.},
      title={First-principles investigation of Ag-, Co-, Cr-, Cu-, Fe-, Mn-, Ni-, Pd- and Rh-hexaaminobenzene 2D metal-organic frameworks},
      journal={Materials Today Energy},
      year={2018},
      volume={10},
      pages={336-342},
      doi={10.1016/j.mtener.2018.10.007},
      note={cited By 16},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85055903192&doi=10.1016%2fj.mtener.2018.10.007&partnerID=40&md5=0d928d60544402964d33fc4f911b01c9},
      affiliation={Institute of Structural Mechanics, Bauhaus-Universität Weimar, Marienstr. 15, Weimar, D-99423, Germany; Department of Materials Science and Engineering, University of Toronto, 184 College Street, Suite 140, Toronto, ON M5S 3E4, Canada; Institute for Materials Science, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, D-01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Department of Computer Engineering, College of Computer and Information Sciences, King Saud University, Riyadh, Saudi Arabia},
      abstract={Hexaaminobenzene (HAB)-derived two-dimensional metal−organic frameworks (MOFs) (Nature Energy 3(2018), 30–36) have most recently gained remarkable attentions as a novel class of two-dimensional (2D) materials, with outstanding performances for advanced energy storage systems. In the latest experimental advances, Ni-, Co- and Cu-HAB MOFs were synthesized in 2D forms, with high electrical conductivities and capacitances as well. Motivated by these experimental advances, we employed first-principles simulations to explore the mechanical, thermal stability and electronic properties of single-layer Ag-, Co-, Cr-, Cu-, Fe-, Mn-, Ni-, Pd- and Rh-HAB MOFs. Theoretical results reveal that Co-, Cr-, Fe-, Mn-, Ni-, Pd- and Rh-HAB nanosheets exhibit linear elasticity with considerable tensile strengths. Ab-initio molecular dynamics results confirm the high thermal stability of all studied nanomembranes. Co- and Fe-HAB monolayers show metallic behavior with low spin-polarization at the Fermi level. Single-layer Ag-, Cu-, Cr-, and Mn-HAB however yield perfect half-metallic behaviors, thus can be promising candidates for the spintronics. In contrast, Ni-, Pd- and Rh-HAB monolayers exhibit nonmagnetic metallic behavior. The insights provided by this investigation confirm the stability and highlight the outstanding physics of transition metal-HAB nanosheets, which are not only highly attractive for the energy storage systems, but may also serve for other advanced applications, like spintronics. © 2018 Elsevier Ltd},
      author_keywords={2D materials; Energy storage; First-principles; MOFs},
      keywords={Crystalline materials; Electronic properties; Energy storage; Molecular dynamics; Monolayers; Nanosheets; Organometallics; Spin polarization; Tensile strength; Thermodynamic stability; Transition metals, Ab initio molecular dynamics; Energy storage systems; First principles; First-principles investigations; First-principles simulations; Half-metallic behavior; High electrical conductivity; MOFs, Storage (materials)},
      correspondence_address1={Mortazavi, B.; Institute of Structural Mechanics, Marienstr. 15, Germany; email: bohayra.mortazavi@gmail.com},
      publisher={Elsevier Ltd},
      issn={24686069},
      language={English},
      abbrev_source_title={Mater. Today Energy},
      document_type={Article},
      source={Scopus},
      }

  • Polymerization driven monomer passage through monolayer chemical vapour deposition graphene
    • T. Zhang, Z. Liao, L. M. Sandonas, A. Dianat, X. Liu, P. Xiao, I. Amin, R. Gutierrez, T. Chen, E. Zschech, G. Cuniberti, R. Jordan
    • Nature Communications 9, 4051 (2018)
    • DOI   Abstract  

      Mass transport through graphene is receiving increasing attention due to the potential for molecular sieving. Experimental studies are mostly limited to the translocation of protons, ions, and water molecules, and results for larger molecules through graphene are rare. Here, we perform controlled radical polymerization with surface-anchored self-assembled initiator monolayer in a monomer solution with single-layer graphene separating the initiator from the monomer. We demonstrate that neutral monomers are able to pass through the graphene (via native defects) and increase the graphene defects ratio (Raman ID/IG) from ca. 0.09 to 0.22. The translocations of anionic and cationic monomers through graphene are significantly slower due to chemical interactions of monomers with the graphene defects. Interestingly, if micropatterned initiator-monolayers are used, the translocations of anionic monomers apparently cut the graphene sheet into congruent microscopic structures. The varied interactions between monomers and graphene defects are further investigated by quantum molecular dynamics simulations. © 2018, The Author(s).

      @ARTICLE{Zhang2018,
      author={Zhang, T. and Liao, Z. and Sandonas, L.M. and Dianat, A. and Liu, X. and Xiao, P. and Amin, I. and Gutierrez, R. and Chen, T. and Zschech, E. and Cuniberti, G. and Jordan, R.},
      title={Polymerization driven monomer passage through monolayer chemical vapour deposition graphene},
      journal={Nature Communications},
      year={2018},
      volume={9},
      number={1},
      doi={10.1038/s41467-018-06599-y},
      art_number={4051},
      note={cited By 14},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054315476&doi=10.1038%2fs41467-018-06599-y&partnerID=40&md5=0bb37ba4bb6e11a7cdeb051ba83a80dc},
      affiliation={Chair of Macromolecular Chemistry, Faculty of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstr. 4, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden, 01062, Germany; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01062, Germany; Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), Maria-Reiche-Straße 2, Dresden, 01109, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany; Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden, 01069, Germany; Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China; Junior Research Group Biosensing Surfaces, Leibniz Institute for Plasma Science and Technology, INP Greifswald e.V., Felix-Hausdorff-Strasse 2, Greifswald, 17489, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={Mass transport through graphene is receiving increasing attention due to the potential for molecular sieving. Experimental studies are mostly limited to the translocation of protons, ions, and water molecules, and results for larger molecules through graphene are rare. Here, we perform controlled radical polymerization with surface-anchored self-assembled initiator monolayer in a monomer solution with single-layer graphene separating the initiator from the monomer. We demonstrate that neutral monomers are able to pass through the graphene (via native defects) and increase the graphene defects ratio (Raman ID/IG) from ca. 0.09 to 0.22. The translocations of anionic and cationic monomers through graphene are significantly slower due to chemical interactions of monomers with the graphene defects. Interestingly, if micropatterned initiator-monolayers are used, the translocations of anionic monomers apparently cut the graphene sheet into congruent microscopic structures. The varied interactions between monomers and graphene defects are further investigated by quantum molecular dynamics simulations. © 2018, The Author(s).},
      keywords={carbon; experimental study; molecular analysis; polymerization; quantum mechanics; vapor pressure},
      correspondence_address1={Zhang, T.; Chair of Macromolecular Chemistry, Mommsenstr. 4, Germany; email: tao.zhang@tu-dresden.de},
      publisher={Nature Publishing Group},
      issn={20411723},
      pubmed_id={30282989},
      language={English},
      abbrev_source_title={Nat. Commun.},
      document_type={Article},
      source={Scopus},
      }

  • Inducing the controlled rotation of single o-MeO-DMBI molecules anchored on Au(111)
    • F. Eisenhut, J. Meyer, J. Krüger, R. Ohmann, G. Cuniberti, F. Moresco
    • Surface Science 678, 177-182 (2018)
    • DOI   Abstract  

      A key step towards building single molecule machines is to control the rotation of molecules and nanostructures step by step on a surface. Here, we used the tunneling electrons coming from the tip of a scanning tunneling microscope to achieve the controlled directed rotation of complex o-MeO-DMBI molecules. We studied the adsorption of single o-MeO-DMBI molecules on Au(111) by scanning tunneling microscopy at low temperature. The enantiomeric form of the molecule on the surface can be determined by imaging the molecule by STM at high bias voltage. We observed by lateral manipulation experiments that the molecules chemisorb on the surface and are anchored on Au(111) with an oxygen-gold bond via their methoxy‑group. Driven by inelastic tunneling electrons, o-MeO-DMBI molecules can controllably rotate, stepwise and unidirectional, either clockwise or counterclockwise depending on their enantiomeric form. © 2018

      @ARTICLE{Eisenhut2018177,
      author={Eisenhut, F. and Meyer, J. and Krüger, J. and Ohmann, R. and Cuniberti, G. and Moresco, F.},
      title={Inducing the controlled rotation of single o-MeO-DMBI molecules anchored on Au(111)},
      journal={Surface Science},
      year={2018},
      volume={678},
      pages={177-182},
      doi={10.1016/j.susc.2018.05.003},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047080490&doi=10.1016%2fj.susc.2018.05.003&partnerID=40&md5=56d788a09db44795f86308c70896aabc},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={A key step towards building single molecule machines is to control the rotation of molecules and nanostructures step by step on a surface. Here, we used the tunneling electrons coming from the tip of a scanning tunneling microscope to achieve the controlled directed rotation of complex o-MeO-DMBI molecules. We studied the adsorption of single o-MeO-DMBI molecules on Au(111) by scanning tunneling microscopy at low temperature. The enantiomeric form of the molecule on the surface can be determined by imaging the molecule by STM at high bias voltage. We observed by lateral manipulation experiments that the molecules chemisorb on the surface and are anchored on Au(111) with an oxygen-gold bond via their methoxy‑group. Driven by inelastic tunneling electrons, o-MeO-DMBI molecules can controllably rotate, stepwise and unidirectional, either clockwise or counterclockwise depending on their enantiomeric form. © 2018},
      author_keywords={Adsorption; Manipulation; Molecular rotor; Scanning tunneling microscopy (STM); Voltage pulses},
      keywords={Adsorption; Enantiomers; Gold metallography; Scanning tunneling microscopy; Temperature, Au(1 1 1 ); Inelastic tunneling; Lateral manipulations; Low temperatures; Manipulation; Molecular rotors; Single molecule; Voltage pulse, Molecules},
      correspondence_address1={Moresco, F.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: francesca.moresco@tu-dresden.de},
      publisher={Elsevier B.V.},
      issn={00396028},
      coden={SUSCA},
      language={English},
      abbrev_source_title={Surf Sci},
      document_type={Article},
      source={Scopus},
      }

  • Diversification of Device Platforms by Molecular Layers: Hybrid Sensing Platforms, Monolayer Doping, and Modeling
    • S. Yitzchaik, R. Gutierrez, G. Cuniberti, R. Yerushalmi
    • Langmuir 34, 14103-14123 (2018)
    • DOI   Abstract  

      Inorganic materials such as semiconductors, oxides, and metals are ubiquitous in a wide range of device technologies owing to the outstanding robustness and mature processing technologies available for such materials. However, while the important contribution of inorganic materials to the advancement of device technologies has been well established for decades, organic-inorganic hybrid device systems, which merge molecular functionalities with inorganic platforms, represent a newer domain that is rapidly evolving at an increasing pace. Such devices benefit from the great versatility and flexibility of the organic building blocks merged with the robustness of the inorganic platforms. Given the overwhelming wealth of literature covering various approaches for modifying and using inorganic devices, this feature article selectively highlights some of the advances made in the context of the diversification of devices by surface chemistry. Particular attention is given to oxide-semiconductor systems and metallic surfaces modified with organic monolayers. The inorganic device components, such as semiconductors, metals, and oxides, are modified by organic monolayers, which may serve as either active, static, or sacrificial components. We portray research directions within the broader field of organic-inorganic hybrid device systems that can be viewed as specific examples of the potential of such hybrid device systems given their comprehensive capabilities of design and diversification. Monolayer doping techniques where sacrificial organic monolayers are introduced into semiconducting elements are reviewed as a specific case, together with associated requirements for nanosystems, devices, and sensors for controlling doping levels and doping profiles on the nanometric scale. Another series of examples of the flexibility provided by the marriage of organic functional monolayers and inorganic device components are represented by a new class of biosensors, where the organic layer functionality is exploited in a functioning device for sensing. Considerations for relying on oxide-terminated semiconductors rather than the pristine semiconductor material as a platform both for processing and sensing are discussed. Finally, we cover aspects related to the use of various theoretical and computational approaches to model organic-inorganic systems. The main objectives of the topics covered here are (i) to present the advances made in each respective domain and (ii) to provide a comprehensive view of the potential uses of organic monolayers and self-assembly processes in the rapidly evolving field of molecular-inorganic hybrid device platforms and processing methodologies. The directions highlighted here provide a perspective on a future, not yet fully realized, integrated approach where organic monolayers are combined with inorganic platforms in order to obtain versatile, robust, and flexible systems with enhanced capabilities. Copyright © 2018 American Chemical Society.

      @ARTICLE{Yitzchaik201814103,
      author={Yitzchaik, S. and Gutierrez, R. and Cuniberti, G. and Yerushalmi, R.},
      title={Diversification of Device Platforms by Molecular Layers: Hybrid Sensing Platforms, Monolayer Doping, and Modeling},
      journal={Langmuir},
      year={2018},
      volume={34},
      number={47},
      pages={14103-14123},
      doi={10.1021/acs.langmuir.8b02369},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054783050&doi=10.1021%2facs.langmuir.8b02369&partnerID=40&md5=eaaf882781c718abe38e0fde124ffe01},
      affiliation={Institute of Chemistry, Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram Jerusalem, 91904, Israel; Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={Inorganic materials such as semiconductors, oxides, and metals are ubiquitous in a wide range of device technologies owing to the outstanding robustness and mature processing technologies available for such materials. However, while the important contribution of inorganic materials to the advancement of device technologies has been well established for decades, organic-inorganic hybrid device systems, which merge molecular functionalities with inorganic platforms, represent a newer domain that is rapidly evolving at an increasing pace. Such devices benefit from the great versatility and flexibility of the organic building blocks merged with the robustness of the inorganic platforms. Given the overwhelming wealth of literature covering various approaches for modifying and using inorganic devices, this feature article selectively highlights some of the advances made in the context of the diversification of devices by surface chemistry. Particular attention is given to oxide-semiconductor systems and metallic surfaces modified with organic monolayers. The inorganic device components, such as semiconductors, metals, and oxides, are modified by organic monolayers, which may serve as either active, static, or sacrificial components. We portray research directions within the broader field of organic-inorganic hybrid device systems that can be viewed as specific examples of the potential of such hybrid device systems given their comprehensive capabilities of design and diversification. Monolayer doping techniques where sacrificial organic monolayers are introduced into semiconducting elements are reviewed as a specific case, together with associated requirements for nanosystems, devices, and sensors for controlling doping levels and doping profiles on the nanometric scale. Another series of examples of the flexibility provided by the marriage of organic functional monolayers and inorganic device components are represented by a new class of biosensors, where the organic layer functionality is exploited in a functioning device for sensing. Considerations for relying on oxide-terminated semiconductors rather than the pristine semiconductor material as a platform both for processing and sensing are discussed. Finally, we cover aspects related to the use of various theoretical and computational approaches to model organic-inorganic systems. The main objectives of the topics covered here are (i) to present the advances made in each respective domain and (ii) to provide a comprehensive view of the potential uses of organic monolayers and self-assembly processes in the rapidly evolving field of molecular-inorganic hybrid device platforms and processing methodologies. The directions highlighted here provide a perspective on a future, not yet fully realized, integrated approach where organic monolayers are combined with inorganic platforms in order to obtain versatile, robust, and flexible systems with enhanced capabilities. Copyright © 2018 American Chemical Society.},
      keywords={Monolayers; Nanosystems; Oxide semiconductors; Self assembly; Semiconductor doping; Surface chemistry, Computational approach; Device technologies; Functioning devices; Integrated approach; Organic-inorganic hybrid devices; Processing technologies; Self assembly process; Semiconductor systems, organic-inorganic materials},
      correspondence_address1={Yerushalmi, R.; Institute of Chemistry, Israel; email: roie.yerushalmi@mail.huji.ac.il},
      publisher={American Chemical Society},
      issn={07437463},
      coden={LANGD},
      pubmed_id={30253096},
      language={English},
      abbrev_source_title={Langmuir},
      document_type={Article},
      source={Scopus},
      }

  • A comparative analysis of symmetric diketopyrrolopyrrole-cored small conjugated molecules with aromatic flanks: From geometry to charge transport
    • D. Raychev, G. Seifert, J. -U. Sommer, O. Guskova
    • Journal of Computational Chemistry 39, 2526-2538 (2018)
    • DOI   Abstract  

      Diketopyrrolopyrrole (DPP) derivatives are promising compounds for application in organic electronics. Here, we investigate several symmetrical N-unsubstituted and N-methyl substituted DPPs which differ in the heteroatom in the aromatic flanks. The conformational, electronic, and optical properties are characterized for single molecules in vacuum or a solvent. The intermolecular interactions are evaluated for interacting dimers. Here, a number of stacking geometries is tested, and dimers with mutual orientation of the molecules corresponding to the minimal binding energies are determined. The predicted charge carrier mobilities for stacks having minimal binding energies corroborate experimentally measured values. We conclude that DFT prediction of such stacks is a promising and computationally inexpensive approach to a rough estimation of transport properties. Additionally, the super-cell of the experimentally resolved crystal structure is used to study the dynamics and to compute the charge transport along the hopping pathways. We discuss obtained high mobilities and relate them to the symmetry of DPP core. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

      @ARTICLE{Raychev20182526,
      author={Raychev, D. and Seifert, G. and Sommer, J.-U. and Guskova, O.},
      title={A comparative analysis of symmetric diketopyrrolopyrrole-cored small conjugated molecules with aromatic flanks: From geometry to charge transport},
      journal={Journal of Computational Chemistry},
      year={2018},
      volume={39},
      number={30},
      pages={2526-2538},
      doi={10.1002/jcc.25609},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054765258&doi=10.1002%2fjcc.25609&partnerID=40&md5=ec88323d12b92d1c81d35a53c7ffc616},
      affiliation={Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, Germany; Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, Germany; Theoretical Chemistry, Technische Universität Dresden, Dresden, 01062, Germany; Institute of Theoretical Physics, Technische Universität Dresden, Zellescher Weg 17, Dresden, 01069, Germany},
      abstract={Diketopyrrolopyrrole (DPP) derivatives are promising compounds for application in organic electronics. Here, we investigate several symmetrical N-unsubstituted and N-methyl substituted DPPs which differ in the heteroatom in the aromatic flanks. The conformational, electronic, and optical properties are characterized for single molecules in vacuum or a solvent. The intermolecular interactions are evaluated for interacting dimers. Here, a number of stacking geometries is tested, and dimers with mutual orientation of the molecules corresponding to the minimal binding energies are determined. The predicted charge carrier mobilities for stacks having minimal binding energies corroborate experimentally measured values. We conclude that DFT prediction of such stacks is a promising and computationally inexpensive approach to a rough estimation of transport properties. Additionally, the super-cell of the experimentally resolved crystal structure is used to study the dynamics and to compute the charge transport along the hopping pathways. We discuss obtained high mobilities and relate them to the symmetry of DPP core. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.},
      author_keywords={charge transport; DFT; diketopyrrolopyrrole; flanks; MD},
      keywords={Aromatic compounds; Carrier mobility; Carrier transport; Charge transfer; Crystal structure; Dimers; Geometry; Mendelevium; Molecules; Optical properties, Comparative analysis; Conjugated molecules; Diketopyrrolopyrroles; flanks; Intermolecular interactions; Mutual orientation; Organic electronics; Rough estimation, Binding energy},
      correspondence_address1={Guskova, O.; Dresden Center for Computational Materials Science (DCMS), Germany; email: guskova@ipfdd.de},
      publisher={John Wiley and Sons Inc.},
      issn={01928651},
      coden={JCCHD},
      pubmed_id={30306613},
      language={English},
      abbrev_source_title={J. Comput. Chem.},
      document_type={Article},
      source={Scopus},
      }

  • Strong Effect of Hydrogen Order on Magnetic Kitaev Interactions in H3LiIr2 O6
    • R. Yadav, R. Ray, M. S. Eldeeb, S. Nishimoto, L. Hozoi, J. Van Den Brink
    • Physical Review Letters 121, 197203 (2018)
    • DOI   Abstract  

      Very recently a quantum liquid was reported to form in H3LiIr2O6, an iridate proposed to be a close realization of the Kitaev honeycomb model. To test this assertion we perform detailed quantum chemistry calculations to determine the magnetic interactions between Ir moments. We find that weakly bond dependent ferromagnetic Kitaev exchange dominates over other couplings, but still is substantially lower than in Na2IrO3. This reduction is caused by the peculiar position of the interlayer species: removing hydrogen cations next to a Ir2O2 plaquette increases the Kitaev exchange by more than a factor of 3 on the corresponding Ir-Ir link. Consequently, any lack of hydrogen order will have a drastic effect on the magnetic interactions and strongly promote spin disordering. © 2018 American Physical Society.

      @ARTICLE{Yadav2018,
      author={Yadav, R. and Ray, R. and Eldeeb, M.S. and Nishimoto, S. and Hozoi, L. and Van Den Brink, J.},
      title={Strong Effect of Hydrogen Order on Magnetic Kitaev Interactions in H3LiIr2 O6},
      journal={Physical Review Letters},
      year={2018},
      volume={121},
      number={19},
      doi={10.1103/PhysRevLett.121.197203},
      art_number={197203},
      note={cited By 37},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056518199&doi=10.1103%2fPhysRevLett.121.197203&partnerID=40&md5=396fad1c07cd192db8929fcb94cf3fdf},
      affiliation={Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Department of Physics, Technical University Dresden, Dresden, 01062, Germany},
      abstract={Very recently a quantum liquid was reported to form in H3LiIr2O6, an iridate proposed to be a close realization of the Kitaev honeycomb model. To test this assertion we perform detailed quantum chemistry calculations to determine the magnetic interactions between Ir moments. We find that weakly bond dependent ferromagnetic Kitaev exchange dominates over other couplings, but still is substantially lower than in Na2IrO3. This reduction is caused by the peculiar position of the interlayer species: removing hydrogen cations next to a Ir2O2 plaquette increases the Kitaev exchange by more than a factor of 3 on the corresponding Ir-Ir link. Consequently, any lack of hydrogen order will have a drastic effect on the magnetic interactions and strongly promote spin disordering. © 2018 American Physical Society.},
      keywords={Binary alloys; Magnetism; Quantum chemistry; Synthetic metals, Effect of hydrogen; Honeycomb models; Hydrogen order; Magnetic interactions; Quantum chemistry calculations; Quantum liquids, Hydrogen},
      publisher={American Physical Society},
      issn={00319007},
      coden={PRLTA},
      pubmed_id={30468592},
      language={English},
      abbrev_source_title={Phys Rev Lett},
      document_type={Article},
      source={Scopus},
      }

  • How do immobilised cell-adhesive Arg–Gly–Asp-containing peptides behave at the PAA brush surface?
    • O. Guskova, V. Savchenko, U. König, P. Uhlmann, J. -U. Sommer
    • Molecular Simulation 44, 1325-1337 (2018)
    • DOI   Abstract  

      Bio-engineered surfaces that aim to induce normal cell behaviour in vitro need to ‘mimic’ the extracellular matrix in a way that allows cell adhesion. In this computational work, several model cell-binding peptides with a minimal cell-adhesive Arg–Gly–Asp sequence are investigated in the bulk as well as immobilised on a soft surface. For this reason, a combination of density functional theory and all-atom MD simulations is applied. The major goal of the modelling is to characterise the accessibility of the cell-recognition motif on the functionalised soft polymer surface. As a reference system, the behaviour of three peptide sequences is preliminarily studied in explicit water simulations. From the analysis of the MD trajectories, the solvent accessible surface area, the distribution of water molecules around peptide groups, the secondary structure and the thermodynamics of hydration are evaluated. Furthermore, each peptide is immobilised on the surface of a homopolymer poly(acrylic acid) brush. During MD simulations, all three peptides approach closely toward PAA brush, and their surface accessibility is characterised. Although the peptides are adsorbed onto the brush, they are not hidden by the polymer strands, with RGD unit accessible on the surface and available for guided cell adhesion. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

      @ARTICLE{Guskova20181325,
      author={Guskova, O. and Savchenko, V. and König, U. and Uhlmann, P. and Sommer, J.-U.},
      title={How do immobilised cell-adhesive Arg–Gly–Asp-containing peptides behave at the PAA brush surface?},
      journal={Molecular Simulation},
      year={2018},
      volume={44},
      number={16},
      pages={1325-1337},
      doi={10.1080/08927022.2018.1502429},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052052394&doi=10.1080%2f08927022.2018.1502429&partnerID=40&md5=935428c7a0c7afa026ee3d2c6e4a885b},
      affiliation={Leibniz Institut für Polymerforschung Dresden e.V., Dresden, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany; Fakultät Umweltwissenschaften, Technische Universität Dresden, Dresden, Germany; Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, United States; Institut für Theoretische Physik, Technische Universität Dresden, Dresden, Germany},
      abstract={Bio-engineered surfaces that aim to induce normal cell behaviour in vitro need to ‘mimic’ the extracellular matrix in a way that allows cell adhesion. In this computational work, several model cell-binding peptides with a minimal cell-adhesive Arg–Gly–Asp sequence are investigated in the bulk as well as immobilised on a soft surface. For this reason, a combination of density functional theory and all-atom MD simulations is applied. The major goal of the modelling is to characterise the accessibility of the cell-recognition motif on the functionalised soft polymer surface. As a reference system, the behaviour of three peptide sequences is preliminarily studied in explicit water simulations. From the analysis of the MD trajectories, the solvent accessible surface area, the distribution of water molecules around peptide groups, the secondary structure and the thermodynamics of hydration are evaluated. Furthermore, each peptide is immobilised on the surface of a homopolymer poly(acrylic acid) brush. During MD simulations, all three peptides approach closely toward PAA brush, and their surface accessibility is characterised. Although the peptides are adsorbed onto the brush, they are not hidden by the polymer strands, with RGD unit accessible on the surface and available for guided cell adhesion. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.},
      author_keywords={density functional theory; molecular dynamics simulation; PAA brush; RGD peptide; thermodynamics of hydration},
      keywords={Bioinformatics; Cell adhesion; Cell culture; Cells; Computation theory; Hydration; Molecular dynamics; Molecules; Peptides; Thermodynamics, Cell recognition motif; Distribution of water; Extracellular matrices; Molecular dynamics simulations; Poly(acrylic acid ); RGD peptide; Secondary structures; Solvent accessible surface areas, Density functional theory},
      correspondence_address1={Guskova, O.; Leibniz Institut für Polymerforschung Dresden e.V.Germany; email: guskova@ipfdd.de},
      publisher={Taylor and Francis Ltd.},
      issn={08927022},
      coden={MOSIE},
      language={English},
      abbrev_source_title={Mol. Simul.},
      document_type={Article},
      source={Scopus},
      }

  • Time-dependent framework for energy and charge currents in nanoscale systems
    • T. Lehmann, A. Croy, R. Gutiérrez, G. Cuniberti
    • Chemical Physics 514, 176-182 (2018)
    • DOI   Abstract  

      The calculation of time-dependent charge and energy currents in nanoscale systems is a challenging task. Nevertheless it is crucial for gaining a deep understanding of the relevant processes at the nanoscale. We extend the auxiliary-mode approach for time-dependent charge transport to allow for the calculation of energy currents for arbitrary time dependencies. We apply the approach to two illustrative examples, a single-level system and a benzene ring, demonstrating its usefulness for a wide range of problems beyond simple toy models, such as molecular devices. © 2018 Elsevier B.V.

      @ARTICLE{Lehmann2018176,
      author={Lehmann, T. and Croy, A. and Gutiérrez, R. and Cuniberti, G.},
      title={Time-dependent framework for energy and charge currents in nanoscale systems},
      journal={Chemical Physics},
      year={2018},
      volume={514},
      pages={176-182},
      doi={10.1016/j.chemphys.2018.01.011},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040933262&doi=10.1016%2fj.chemphys.2018.01.011&partnerID=40&md5=18e35e84dfc2d92de43154f90476c061},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={The calculation of time-dependent charge and energy currents in nanoscale systems is a challenging task. Nevertheless it is crucial for gaining a deep understanding of the relevant processes at the nanoscale. We extend the auxiliary-mode approach for time-dependent charge transport to allow for the calculation of energy currents for arbitrary time dependencies. We apply the approach to two illustrative examples, a single-level system and a benzene ring, demonstrating its usefulness for a wide range of problems beyond simple toy models, such as molecular devices. © 2018 Elsevier B.V.},
      author_keywords={Charge current; Energy current; Non-adiabatic; Time-dependent},
      correspondence_address1={Croy, A.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: alexander.croy@tu-dresden.de},
      publisher={Elsevier B.V.},
      issn={03010104},
      coden={CMPHC},
      language={English},
      abbrev_source_title={Chem. Phys.},
      document_type={Article},
      source={Scopus},
      }

  • Thermal Decoherence and Disorder Effects on Chiral-Induced Spin Selectivity
    • E. Díaz, F. Domínguez-Adame, R. Gutierrez, G. Cuniberti, V. Mujica
    • Journal of Physical Chemistry Letters 9, 5753-5758 (2018)
    • DOI   Abstract  

      We use a nonlinear master equation formalism to account for thermal and disorder effects on spin-dependent electron transport in helical organic molecules coupled to two ideal leads. The inclusion of these two effects has important consequences in understanding the observed length and temperature dependence of spin polarization in experiments, which cannot be accounted for in a purely coherent tunneling model. Our approach considers a tight-binding helical Hamiltonian with disordered onsite energies to describe the resulting electronic states when low-frequency interacting modes break the electron coherence. The high-frequency fluctuating counterpart of these interactions, typical of intramolecular modes, is included by means of temperature-dependent thermally activated transfer probabilities in the master equation, which lead to hopping between localized states. We focus on the spin-dependent conductance and the spin-polarization in the linear regime (low voltage), which are analyzed as a function of the molecular length and the temperature of the system. Our results at room temperature agree well with experiments because our model predicts that the degree of spin-polarization increases for longer molecules. Also, this effect is temperature-dependent because thermal excitation competes with disorder-induced Anderson localization. We conclude that a transport mechanism based on thermally activated hopping in a disordered system can account for the unexpected behavior of the spin polarization. © 2018 American Chemical Society.

      @ARTICLE{Díaz20185753,
      author={Díaz, E. and Domínguez-Adame, F. and Gutierrez, R. and Cuniberti, G. and Mujica, V.},
      title={Thermal Decoherence and Disorder Effects on Chiral-Induced Spin Selectivity},
      journal={Journal of Physical Chemistry Letters},
      year={2018},
      volume={9},
      number={19},
      pages={5753-5758},
      doi={10.1021/acs.jpclett.8b02196},
      note={cited By 20},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053891550&doi=10.1021%2facs.jpclett.8b02196&partnerID=40&md5=2cf3e4e1e8d053f4dff09d3b877acab8},
      affiliation={GISC, Departamento de Física de Materiales, Universidad Complutense, Madrid, E-28040, Spain; Institute for Materials Science, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, United States},
      abstract={We use a nonlinear master equation formalism to account for thermal and disorder effects on spin-dependent electron transport in helical organic molecules coupled to two ideal leads. The inclusion of these two effects has important consequences in understanding the observed length and temperature dependence of spin polarization in experiments, which cannot be accounted for in a purely coherent tunneling model. Our approach considers a tight-binding helical Hamiltonian with disordered onsite energies to describe the resulting electronic states when low-frequency interacting modes break the electron coherence. The high-frequency fluctuating counterpart of these interactions, typical of intramolecular modes, is included by means of temperature-dependent thermally activated transfer probabilities in the master equation, which lead to hopping between localized states. We focus on the spin-dependent conductance and the spin-polarization in the linear regime (low voltage), which are analyzed as a function of the molecular length and the temperature of the system. Our results at room temperature agree well with experiments because our model predicts that the degree of spin-polarization increases for longer molecules. Also, this effect is temperature-dependent because thermal excitation competes with disorder-induced Anderson localization. We conclude that a transport mechanism based on thermally activated hopping in a disordered system can account for the unexpected behavior of the spin polarization. © 2018 American Chemical Society.},
      keywords={Electron transport properties; Molecules; Nonlinear equations; Stereochemistry; Temperature distribution, Anderson localization; Spin-dependent conductance; Spin-dependent electron transport; Temperature dependence; Temperature dependent; Thermally activated; Thermally activated hopping; Transfer probability, Spin polarization},
      correspondence_address1={Díaz, E.; GISC, Spain; email: elenadg@ucm.es},
      publisher={American Chemical Society},
      issn={19487185},
      pubmed_id={30212207},
      language={English},
      abbrev_source_title={J. Phys. Chem. Lett.},
      document_type={Article},
      source={Scopus},
      }

  • Electronic transport through defective semiconducting carbon nanotubes
    • F. Teichert, A. Zienert, J. Schuster, M. Schreiber
    • Journal of Physics Communications 2, 105012 (2018)
    • DOI   Abstract  

      We investigate the electronic transport properties of semiconducting (m, n) carbon nanotubes (CNTs) on the mesoscopic length scale with arbitrarily distributed realistic defects. The study is done by performing quantum transport calculations based on recursive Green’s function techniques and an underlying density-functional-based tight-binding model for the description of the electronic structure. Zigzag CNTs as well as chiral CNTs of different diameter are considered. Different defects are exemplarily represented by monovacancies and divacancies. We show the energy-dependent transmission and the temperature-dependent conductance as a function of the number of defects. In the limit of many defetcs, the transport is described by strong localization. Corresponding localization lengths are calculated (energy dependent and temperature dependent) and systematically compared for a large number of CNTs. It is shown, that a distinction by (m−n)mod 3 has to be drawn in order to classify CNTs with different bandgaps. Besides this, the localization length for a given defect probability per unit cell depends linearly on the CNT diameter, but not on the CNT chirality. Finally, elastic mean free paths in the diffusive regime are computed for the limit of few defects, yielding qualitatively same statements. © 2018 The Author(s).

      @ARTICLE{Teichert2018,
      author={Teichert, F. and Zienert, A. and Schuster, J. and Schreiber, M.},
      title={Electronic transport through defective semiconducting carbon nanotubes},
      journal={Journal of Physics Communications},
      year={2018},
      volume={2},
      number={10},
      doi={10.1088/2399-6528/aae4cb},
      art_number={105012},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070487465&doi=10.1088%2f2399-6528%2faae4cb&partnerID=40&md5=8ced67a24b1295bef618443eb8eb8f6e},
      affiliation={Institute of Physics, Chemnitz University of Technology, Chemnitz, 09107, Germany; Center for Microtechnologies, Chemnitz University of Technology, Chemnitz, 09107, Germany; Fraunhofer Institute for Electronic Nano Systems (ENAS), Chemnitz, 09126, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={We investigate the electronic transport properties of semiconducting (m, n) carbon nanotubes (CNTs) on the mesoscopic length scale with arbitrarily distributed realistic defects. The study is done by performing quantum transport calculations based on recursive Green’s function techniques and an underlying density-functional-based tight-binding model for the description of the electronic structure. Zigzag CNTs as well as chiral CNTs of different diameter are considered. Different defects are exemplarily represented by monovacancies and divacancies. We show the energy-dependent transmission and the temperature-dependent conductance as a function of the number of defects. In the limit of many defetcs, the transport is described by strong localization. Corresponding localization lengths are calculated (energy dependent and temperature dependent) and systematically compared for a large number of CNTs. It is shown, that a distinction by (m−n)mod 3 has to be drawn in order to classify CNTs with different bandgaps. Besides this, the localization length for a given defect probability per unit cell depends linearly on the CNT diameter, but not on the CNT chirality. Finally, elastic mean free paths in the diffusive regime are computed for the limit of few defects, yielding qualitatively same statements. © 2018 The Author(s).},
      author_keywords={Carbon nanotube (CNT); Defect; Density-functional-based tight binding (DFTB); Elastic mean free path; Electronic transport; Recursive Greenʼs function formalism (RGF); Strong localization},
      correspondence_address1={Teichert, F.; Institute of Physics, Germany; email: fabian.teichert@physik.tu-chemnitz.de},
      publisher={Institute of Physics Publishing},
      issn={23996528},
      language={English},
      abbrev_source_title={J. Phy. Commun.},
      document_type={Article},
      source={Scopus},
      }

  • Tuning the conductance of a molecular wire by the interplay of donor and acceptor units
    • D. Skidin, T. Erdmann, S. Nikipar, F. Eisenhut, J. Krüger, F. Günther, S. Gemming, A. Kiriy, B. Voit, D. A. Ryndyk, C. Joachim, F. Moresco, G. Cuniberti
    • Nanoscale 10, 17131-17139 (2018)
    • DOI   Abstract  

      We investigate the conductance of optimized donor-acceptor-donor molecular wires obtained by on-surface synthesis on the Au(111) surface. A careful balance between acceptors and donors is achieved using a diketopyrrolopyrrole acceptor and two thiophene donors per unit along the wire. Scanning tunneling microscopy imaging, spectroscopy, and conductance measurements done by pulling a single molecular wire at one end are presented. We show that the conductance of the obtained wires is among the highest reported so far in a tunneling transport regime, with an inverse decay length of 0.17 Å−1. Using complex band structure calculations, different donor and acceptor groups are discussed, showing how a balanced combination of donor and acceptor units along the wire can further minimize the decay of the tunneling current with length. © The Royal Society of Chemistry.

      @ARTICLE{Skidin201817131,
      author={Skidin, D. and Erdmann, T. and Nikipar, S. and Eisenhut, F. and Krüger, J. and Günther, F. and Gemming, S. and Kiriy, A. and Voit, B. and Ryndyk, D.A. and Joachim, C. and Moresco, F. and Cuniberti, G.},
      title={Tuning the conductance of a molecular wire by the interplay of donor and acceptor units},
      journal={Nanoscale},
      year={2018},
      volume={10},
      number={36},
      pages={17131-17139},
      doi={10.1039/c8nr05031g},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054036347&doi=10.1039%2fc8nr05031g&partnerID=40&md5=f9b2aea21dadc867acfb338b665690d5},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Leibniz-Institut für Polymerforschung Dresden e.V., Dresden, 01069, Germany; Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, Dresden, 01328, Germany; Institute of Physics, TU Chemnitz, Chemnitz, 09107, Germany; Bremen Center for Computational Materials Science, Department of Physics, Universität Bremen, Bremen, 28359, Germany; GNS and MANA Satellite, CEMES, CNRS, 29 rue J. Marvig, Toulouse Cedex, 31055, France; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={We investigate the conductance of optimized donor-acceptor-donor molecular wires obtained by on-surface synthesis on the Au(111) surface. A careful balance between acceptors and donors is achieved using a diketopyrrolopyrrole acceptor and two thiophene donors per unit along the wire. Scanning tunneling microscopy imaging, spectroscopy, and conductance measurements done by pulling a single molecular wire at one end are presented. We show that the conductance of the obtained wires is among the highest reported so far in a tunneling transport regime, with an inverse decay length of 0.17 Å−1. Using complex band structure calculations, different donor and acceptor groups are discussed, showing how a balanced combination of donor and acceptor units along the wire can further minimize the decay of the tunneling current with length. © The Royal Society of Chemistry.},
      keywords={Nanowires; Scanning tunneling microscopy, Au(111) surfaces; Complex band structures; Conductance measurement; Diketopyrrolopyrroles; Donor acceptor donors; Donor and acceptor; Tunneling current; Tunneling transports, Wire},
      correspondence_address1={Moresco, F.; Institute for Materials Science, Germany; email: francesca.moresco@tu-dresden.de},
      publisher={Royal Society of Chemistry},
      issn={20403364},
      pubmed_id={30182095},
      language={English},
      abbrev_source_title={Nanoscale},
      document_type={Article},
      source={Scopus},
      }

  • Enhanced Magnetoresistance in Chiral Molecular Junctions
    • V. V. Maslyuk, R. Gutierrez, A. Dianat, V. Mujica, G. Cuniberti
    • Journal of Physical Chemistry Letters 9, 5453-5459 (2018)
    • DOI   Abstract  

      Chirality-induced spin selectivity (CISS) is a recently discovered effect, whose precise microscopic origin has not yet been fully elucidated; it seems, however, clear that spin-orbit interaction plays a pivotal role. Various model Hamiltonian approaches have been proposed, suggesting a close connection between spin selectivity and filtering and helical symmetry. However, first-principles studies revealing the influence of chirality on the spin polarization are missing. To clearly demonstrate the influence of the helical conformation on the spin polarization properties, we have carried out spin-dependent Density-Functional Theory (DFT) based transport calculations for a model molecular system. It consists of α-helix and β-strand conformations of an oligo-glycine peptide, which is bonded to a nickel electrode and to a gold electrode in a two-terminal setup, similar to a molecular junction or a local probe, for example, in STM or AFM configurations. We have found that the α-helix conformation displays a spin polarization, calculated through the intrinsic magneto-resistance of the junction, about 100-1000 times larger than the linear β-strand, clearly demonstrating the crucial role played by the molecular helical geometry on the enhancement of spin polarization associated with the CISS effect. Copyright © 2018 American Chemical Society.

      @ARTICLE{Maslyuk20185453,
      author={Maslyuk, V.V. and Gutierrez, R. and Dianat, A. and Mujica, V. and Cuniberti, G.},
      title={Enhanced Magnetoresistance in Chiral Molecular Junctions},
      journal={Journal of Physical Chemistry Letters},
      year={2018},
      volume={9},
      number={18},
      pages={5453-5459},
      doi={10.1021/acs.jpclett.8b02360},
      note={cited By 56},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053719884&doi=10.1021%2facs.jpclett.8b02360&partnerID=40&md5=79b97c828a89c413fe8bad24e0ce3adf},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, Dresden University of Technology, Dresden, 01062, Germany; Arizona State University, School of Molecular Sciences, PO Box 871604, Tempe, AZ 85287-1604, United States; Dresden Center for Computational Materials Science, Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={Chirality-induced spin selectivity (CISS) is a recently discovered effect, whose precise microscopic origin has not yet been fully elucidated; it seems, however, clear that spin-orbit interaction plays a pivotal role. Various model Hamiltonian approaches have been proposed, suggesting a close connection between spin selectivity and filtering and helical symmetry. However, first-principles studies revealing the influence of chirality on the spin polarization are missing. To clearly demonstrate the influence of the helical conformation on the spin polarization properties, we have carried out spin-dependent Density-Functional Theory (DFT) based transport calculations for a model molecular system. It consists of α-helix and β-strand conformations of an oligo-glycine peptide, which is bonded to a nickel electrode and to a gold electrode in a two-terminal setup, similar to a molecular junction or a local probe, for example, in STM or AFM configurations. We have found that the α-helix conformation displays a spin polarization, calculated through the intrinsic magneto-resistance of the junction, about 100-1000 times larger than the linear β-strand, clearly demonstrating the crucial role played by the molecular helical geometry on the enhancement of spin polarization associated with the CISS effect. Copyright © 2018 American Chemical Society.},
      keywords={Amino acids; Calculations; Chirality; Conformations; Density functional theory; Electrodes; Enhanced magnetoresistance, First-principles study; Helical conformation; Model Hamiltonians; Model molecular systems; Molecular junction; Nickel electrode; Spin orbit interactions; Transport calculation, Spin polarization},
      correspondence_address1={Gutierrez, R.; Institute for Materials Science, Germany; email: rafael.gutierrez@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19487185},
      language={English},
      abbrev_source_title={J. Phys. Chem. Lett.},
      document_type={Article},
      source={Scopus},
      }

  • Growth kinetics and morphological analysis of homoepitaxial GaAs fins by theory and experiment
    • M. Albani, L. Ghisalberti, R. Bergamaschini, M. Friedl, M. Salvalaglio, A. Voigt, F. Montalenti, G. Tütüncüoglu, A. M. I. Fontcuberta, L. Miglio
    • Physical Review Materials 2, 093404 (2018)
    • DOI   Abstract  

      Nanoscale membranes have emerged as a new class of vertical nanostructures that enable the integration of horizontal networks of III-V nanowires on a chip. To generalize this method to the whole family of III-Vs, progress in the understanding of the membrane formation by selective area epitaxy in oxide slits is needed, in particular for different slit orientations. Here, it is demonstrated that the shape is primarily driven by the growth kinetics rather than determined by surface energy minimization as commonly occurs for faceted nanostructures. To this end, a phase-field model simulating the shape evolution during growth is devised, in agreement with the experimental findings for any slit orientations, even when the vertical membranes turn into multifaceted fins. This makes it possible to reverseengineer the facet-dependent incorporation times, which were so far unknown, even for common low-index facets. The compelling reproduction of the experimental morphologies demonstrates the reliability of the growth model and offers a general method to determine microscopic kinetic parameters governing out-of-equilibrium three-dimensional growth. © 2018 American Physical Society.

      @ARTICLE{Albani2018,
      author={Albani, M. and Ghisalberti, L. and Bergamaschini, R. and Friedl, M. and Salvalaglio, M. and Voigt, A. and Montalenti, F. and Tütüncüoglu, G. and Fontcuberta, A.M.I. and Miglio, L.},
      title={Growth kinetics and morphological analysis of homoepitaxial GaAs fins by theory and experiment},
      journal={Physical Review Materials},
      year={2018},
      volume={2},
      number={9},
      doi={10.1103/PhysRevMaterials.2.093404},
      art_number={093404},
      note={cited By 25},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059614245&doi=10.1103%2fPhysRevMaterials.2.093404&partnerID=40&md5=232196bfbf3bc10a2d0a07f673924eae},
      affiliation={L-NESS and Dept. of Materials Science, Università di Milano-Bicocca, Milano, 20125, Italy; Laboratory of Semiconductor Materials, École Polytechnique Fédérale de Lausanne, EPFL, Lausanne, 1015, Switzerland; Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Filler Laboratory, Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, United States},
      abstract={Nanoscale membranes have emerged as a new class of vertical nanostructures that enable the integration of horizontal networks of III-V nanowires on a chip. To generalize this method to the whole family of III-Vs, progress in the understanding of the membrane formation by selective area epitaxy in oxide slits is needed, in particular for different slit orientations. Here, it is demonstrated that the shape is primarily driven by the growth kinetics rather than determined by surface energy minimization as commonly occurs for faceted nanostructures. To this end, a phase-field model simulating the shape evolution during growth is devised, in agreement with the experimental findings for any slit orientations, even when the vertical membranes turn into multifaceted fins. This makes it possible to reverseengineer the facet-dependent incorporation times, which were so far unknown, even for common low-index facets. The compelling reproduction of the experimental morphologies demonstrates the reliability of the growth model and offers a general method to determine microscopic kinetic parameters governing out-of-equilibrium three-dimensional growth. © 2018 American Physical Society.},
      keywords={Fins (heat exchange); Gallium arsenide; III-V semiconductors; Kinetics; Nanostructures; Thermal management (electronics), Energy minimization; Membrane formation; Microscopic kinetics; Morphological analysis; Out of equilibrium; Phase field models; Selective area epitaxy; Three-dimensional growth, Growth kinetics},
      correspondence_address1={Albani, M.; L-NESS and Dept. of Materials Science, Italy},
      publisher={American Physical Society},
      issn={24759953},
      language={English},
      abbrev_source_title={Physic. Rev. Mat.},
      document_type={Article},
      source={Scopus},
      }

  • Microscopic field-theoretical approach for mixtures of active and passive particles
    • F. Alaimo, A. Voigt
    • Physical Review E 98, 032605 (2018)
    • DOI   Abstract  

      We consider a phase field crystal modeling approach for mixtures of interacting active and passive particles in two dimensions. The approach allows us to describe generic properties for such heterogeneous systems within a continuum model. We validate the approach by reproducing experimental results, as well as results obtained with agent-based simulations. The approach is valid for the whole spectrum from highly dilute suspensions of passive particles and interacting active particles in a dense background of passive particles. However, we concentrate only on the extreme cases, because for the situation with similar fractions of active and passive particles emerging structures are hard to analyze and experimental results are missing. We analyze in detail enhanced crystallization due to the presence of active particles, how collective migration is affected by a disordered environment, and laning states, which are globally nematic but polar within each lane. © 2018 American Physical Society.

      @ARTICLE{Alaimo2018,
      author={Alaimo, F. and Voigt, A.},
      title={Microscopic field-theoretical approach for mixtures of active and passive particles},
      journal={Physical Review E},
      year={2018},
      volume={98},
      number={3},
      doi={10.1103/PhysRevE.98.032605},
      art_number={032605},
      note={cited By 19},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053431731&doi=10.1103%2fPhysRevE.98.032605&partnerID=40&md5=c623a9ee9724a8a4dc390b72f310cda6},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Dresden, 01062, Germany; Center of Systems Biology Dresden (CSBD), Pfotenhauerstr. 108, Dresden, 01307, Germany},
      abstract={We consider a phase field crystal modeling approach for mixtures of interacting active and passive particles in two dimensions. The approach allows us to describe generic properties for such heterogeneous systems within a continuum model. We validate the approach by reproducing experimental results, as well as results obtained with agent-based simulations. The approach is valid for the whole spectrum from highly dilute suspensions of passive particles and interacting active particles in a dense background of passive particles. However, we concentrate only on the extreme cases, because for the situation with similar fractions of active and passive particles emerging structures are hard to analyze and experimental results are missing. We analyze in detail enhanced crystallization due to the presence of active particles, how collective migration is affected by a disordered environment, and laning states, which are globally nematic but polar within each lane. © 2018 American Physical Society.},
      keywords={Continuum mechanics; Mixtures, Agent based simulation; Continuum Modeling; Dilute suspensions; Generic properties; Heterogeneous systems; Microscopic fields; Phase field crystal model; Theoretical approach, Suspensions (fluids)},
      publisher={American Physical Society},
      issn={24700045},
      language={English},
      abbrev_source_title={Phys. Rev. E},
      document_type={Article},
      source={Scopus},
      }

  • Atomistic Framework for Time-Dependent Thermal Transport
    • L. Medrano Sandonas, A. Croy, R. Gutierrez, G. Cuniberti
    • Journal of Physical Chemistry C 122, 21062-21068 (2018)
    • DOI   Abstract  

      Phonons play a major role for the performance of nanoscale devices and consequently a detailed understanding of phonon dynamics is required. Using an auxiliary-mode approach, which has successfully been applied for the case of electrons, we develop a new method to numerically describe time-dependent phonon transport. This method allows one to gain insight into the behavior of local vibrations in molecular junctions, which are driven by time-dependent temperature differences between thermal baths. Exemplarily, we apply the method to study the nonequilibrium dynamics of quantum heat transport in an one-dimensional atomic chain as well as in realistic molecular junctions made of polyacetylene and polyethylene chains, in which the vibrational structure of the junction is described at the density functional theory level. We calculate the transient energies and heat currents and compare the latter to the standard Landauer approach in thermal equilibrium. We show that the auxiliary-mode representation is a powerful and versatile tool to study time-dependent thermal transport in nanoscale systems. © 2018 American Chemical Society.

      @ARTICLE{MedranoSandonas201821062,
      author={Medrano Sandonas, L. and Croy, A. and Gutierrez, R. and Cuniberti, G.},
      title={Atomistic Framework for Time-Dependent Thermal Transport},
      journal={Journal of Physical Chemistry C},
      year={2018},
      volume={122},
      number={36},
      pages={21062-21068},
      doi={10.1021/acs.jpcc.8b06598},
      note={cited By 2},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052315007&doi=10.1021%2facs.jpcc.8b06598&partnerID=40&md5=1461b678ee8f02c1d5229fa56f5d5f3b},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany},
      abstract={Phonons play a major role for the performance of nanoscale devices and consequently a detailed understanding of phonon dynamics is required. Using an auxiliary-mode approach, which has successfully been applied for the case of electrons, we develop a new method to numerically describe time-dependent phonon transport. This method allows one to gain insight into the behavior of local vibrations in molecular junctions, which are driven by time-dependent temperature differences between thermal baths. Exemplarily, we apply the method to study the nonequilibrium dynamics of quantum heat transport in an one-dimensional atomic chain as well as in realistic molecular junctions made of polyacetylene and polyethylene chains, in which the vibrational structure of the junction is described at the density functional theory level. We calculate the transient energies and heat currents and compare the latter to the standard Landauer approach in thermal equilibrium. We show that the auxiliary-mode representation is a powerful and versatile tool to study time-dependent thermal transport in nanoscale systems. © 2018 American Chemical Society.},
      keywords={Chains; Ethylene; Nanotechnology; Phonons; Quantum chemistry, Molecular junction; Nano-scale system; Non-equilibrium dynamics; Quantum heat transport; Thermal equilibriums; Thermal transport; Time-dependent temperature; Vibrational structures, Density functional theory},
      correspondence_address1={Croy, A.; Institute for Materials Science, Germany; email: alexander.croy@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19327447},
      language={English},
      abbrev_source_title={J. Phys. Chem. C},
      document_type={Article},
      source={Scopus},
      }

  • Thermodynamically consistent three-dimensional electrochemical model for polymeric membranes
    • M. Rossi, T. Wallmersperger
    • Electrochimica Acta 283, 1323-1338 (2018)
    • DOI   Abstract  

      In this paper, the behavior of an electrochemical thin polymeric film sandwiched between porous electrodes and under input voltage (potentiostatic) conditions is numerically investigated. Thin polymeric membranes, such as Nafion, are widely used in micro-batteries and proton-exchange-membrane fuel cells. A three-dimensional continuum-based multi-field formulation for thin polymeric membranes is presented. The model is applied to configurations of the type electrode-membrane-electrode in order to represent the core of a characteristic electrochemical device. Various three-dimensional geometries are considered. The phenomena modeled within the polymeric membrane are (i) ion transport (chemical field) and (ii) electrical field. The field equations, i.e. the Poisson-Nernst-Planck equations, are determined by inserting the thermodynamically consistent constitutive equations within the balance equations of the electrochemical problem. Suitable initial and boundary conditions have to be imposed in order to solve the system of partial differential equations. In particular, the phenomena modeled at the membrane/electrode interface are (i) the electrochemical kinetics of the chemical reaction and (ii) the polarization effects. Time-dependent numerical simulations for potentiostatic conditions are performed within a finite element framework. It is shown that the presented fully coupled multi-field model reproduces, within a simulation framework, the behavior of electrochemical cells. In fact, the model is capable of well predicting the space and time evolution of the main electrochemical parameters as well as catching multi-dimensional effects. The presented model can be regarded as a starting point to develop further research concerning an electro-chemo-mechanical model in order to well understand the stress distribution which arises in polymeric membranes during operating conditions. © 2018 Elsevier Ltd

      @ARTICLE{Rossi20181323,
      author={Rossi, M. and Wallmersperger, T.},
      title={Thermodynamically consistent three-dimensional electrochemical model for polymeric membranes},
      journal={Electrochimica Acta},
      year={2018},
      volume={283},
      pages={1323-1338},
      doi={10.1016/j.electacta.2018.06.174},
      note={cited By 17},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050159805&doi=10.1016%2fj.electacta.2018.06.174&partnerID=40&md5=d522da5281c20fc0838b594357efa07b},
      affiliation={Institute of Solid Mechanics, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={In this paper, the behavior of an electrochemical thin polymeric film sandwiched between porous electrodes and under input voltage (potentiostatic) conditions is numerically investigated. Thin polymeric membranes, such as Nafion, are widely used in micro-batteries and proton-exchange-membrane fuel cells. A three-dimensional continuum-based multi-field formulation for thin polymeric membranes is presented. The model is applied to configurations of the type electrode-membrane-electrode in order to represent the core of a characteristic electrochemical device. Various three-dimensional geometries are considered. The phenomena modeled within the polymeric membrane are (i) ion transport (chemical field) and (ii) electrical field. The field equations, i.e. the Poisson-Nernst-Planck equations, are determined by inserting the thermodynamically consistent constitutive equations within the balance equations of the electrochemical problem. Suitable initial and boundary conditions have to be imposed in order to solve the system of partial differential equations. In particular, the phenomena modeled at the membrane/electrode interface are (i) the electrochemical kinetics of the chemical reaction and (ii) the polarization effects. Time-dependent numerical simulations for potentiostatic conditions are performed within a finite element framework. It is shown that the presented fully coupled multi-field model reproduces, within a simulation framework, the behavior of electrochemical cells. In fact, the model is capable of well predicting the space and time evolution of the main electrochemical parameters as well as catching multi-dimensional effects. The presented model can be regarded as a starting point to develop further research concerning an electro-chemo-mechanical model in order to well understand the stress distribution which arises in polymeric membranes during operating conditions. © 2018 Elsevier Ltd},
      author_keywords={Electrochemical cell; Finite elements; Thermodynamically based model; Thin membranes; Transport theory},
      keywords={Boundary conditions; Constitutive equations; Electrochemical cells; Finite element method; Polymeric membranes; Proton exchange membrane fuel cells (PEMFC); Reaction kinetics; Statistical mechanics, Electrochemical parameters; Initial and boundary conditions; Poisson-Nernst-Planck equations; Potentiostatic conditions; System of partial differential equations; Thin membrane; Three dimensional geometry; Transport theory, Electrochemical electrodes},
      correspondence_address1={Wallmersperger, T.; Institut für Festkörpermechanik, George-Bähr-Str. 3c, Germany; email: thomas.wallmersperger@tu-dresden.de},
      publisher={Elsevier Ltd},
      issn={00134686},
      coden={ELCAA},
      language={English},
      abbrev_source_title={Electrochim Acta},
      document_type={Article},
      source={Scopus},
      }

  • Electronic Resonances and Gap Stabilization of Higher Acenes on a Gold Surface
    • J. Krüger, F. Eisenhut, D. Skidin, T. Lehmann, D. A. Ryndyk, G. Cuniberti, F. García, J. M. Alonso, E. Guitián, D. Pérez, D. Peña, G. Trinquier, J. -P. Malrieu, F. Moresco, C. Joachim
    • ACS Nano 12, 8506-8511 (2018)
    • DOI   Abstract  

      On-surface synthesis provides a powerful method for the generation of long acene molecules, making possible the detailed investigation of the electronic properties of single higher acenes on a surface. By means of scanning tunneling microscopy and spectroscopy combined with theoretical considerations, we discuss the polyradical character of the ground state of higher acenes as a function of the number of linearly fused benzene rings. We present energy and spatial mapping of the tunneling resonances of hexacene, heptacene, and decacene, and discuss the role of molecular orbitals in the observed tunneling conductance maps. We show that the energy gap between the first electronic tunneling resonances below and above the Fermi energy stabilizes to a finite value, determined by a first diradical electronic perturbative contribution to the polyacene electronic ground state. Up to decacene, the main contributor to the ground state of acenes remains the lowest-energy closed-shell electronic configuration. © 2018 American Chemical Society.

      @ARTICLE{Krüger20188506,
      author={Krüger, J. and Eisenhut, F. and Skidin, D. and Lehmann, T. and Ryndyk, D.A. and Cuniberti, G. and García, F. and Alonso, J.M. and Guitián, E. and Pérez, D. and Peña, D. and Trinquier, G. and Malrieu, J.-P. and Moresco, F. and Joachim, C.},
      title={Electronic Resonances and Gap Stabilization of Higher Acenes on a Gold Surface},
      journal={ACS Nano},
      year={2018},
      volume={12},
      number={8},
      pages={8506-8511},
      doi={10.1021/acsnano.8b04046},
      note={cited By 26},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052332523&doi=10.1021%2facsnano.8b04046&partnerID=40&md5=6503c2899f79167f842c3b71e52628c3},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Bremen Center for Computational Materials Science (BCCMS), Universität Bremen, Bremen, 28359, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain; Laboratoire de Chimie et Physique Quantiques, IRSAMC-CNRS-UMR5626, Université Paul-Sabatier (Toulouse III), Toulouse Cedex 4, 31062, France; Centre d'Élaboration de Matériaux et d'Études Structurale (CEMES), UPR 8011 CNRS, Nanosciences Group and MANA Satellite, 29 Rue J. Marvig, P.O. Box 94347, Toulouse, 31055, France},
      abstract={On-surface synthesis provides a powerful method for the generation of long acene molecules, making possible the detailed investigation of the electronic properties of single higher acenes on a surface. By means of scanning tunneling microscopy and spectroscopy combined with theoretical considerations, we discuss the polyradical character of the ground state of higher acenes as a function of the number of linearly fused benzene rings. We present energy and spatial mapping of the tunneling resonances of hexacene, heptacene, and decacene, and discuss the role of molecular orbitals in the observed tunneling conductance maps. We show that the energy gap between the first electronic tunneling resonances below and above the Fermi energy stabilizes to a finite value, determined by a first diradical electronic perturbative contribution to the polyacene electronic ground state. Up to decacene, the main contributor to the ground state of acenes remains the lowest-energy closed-shell electronic configuration. © 2018 American Chemical Society.},
      author_keywords={acenes; deoxygenation; energy gap; molecular orbitals; molecular resonances; on-surface synthesis; scanning tunneling spectroscopy},
      keywords={Electronic properties; Energy gap; Gold; Molecular orbitals; Resonance; Scanning tunneling microscopy; Synthesis (chemical), acenes; Deoxygenations; Electronic configuration; Electronic ground state; Molecular resonances; Scanning tunneling microscopy and spectroscopy; Scanning tunneling spectroscopy; Tunneling conductance, Ground state, article; deoxygenation; scanning tunneling spectroscopy; synthesis},
      correspondence_address1={Moresco, F.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: francesca.moresco@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19360851},
      pubmed_id={30059612},
      language={English},
      abbrev_source_title={ACS Nano},
      document_type={Article},
      source={Scopus},
      }

  • Hexacene generated on passivated silicon
    • F. Eisenhut, J. Krüger, D. Skidin, S. Nikipar, J. M. Alonso, E. Guitián, D. Pérez, D. A. Ryndyk, D. Peña, F. Moresco, G. Cuniberti
    • Nanoscale 10, 12582-12587 (2018)
    • DOI   Abstract  

      On-surface synthesis represents a successful strategy to obtain designed molecular structures on an ultra-clean metal substrate. While metal surfaces are known to favor adsorption, diffusion, and chemical bonding between molecular groups, on-surface synthesis on non-metallic substrates would allow the electrical decoupling of the resulting molecule from the surface, favoring application to electronics and spintronics. Here, we demonstrate the on-surface generation of hexacene by surface-assisted reduction on a H-passivated Si(001) surface. The reaction, observed by scanning tunneling microscopy and spectroscopy, is probably driven by the formation of Si-O complexes at dangling bond defects. Supported by density functional theory calculations, we investigate the interaction of hexacene with the passivated silicon surface, and with single silicon dangling bonds. © The Royal Society of Chemistry.

      @ARTICLE{Eisenhut201812582,
      author={Eisenhut, F. and Krüger, J. and Skidin, D. and Nikipar, S. and Alonso, J.M. and Guitián, E. and Pérez, D. and Ryndyk, D.A. and Peña, D. and Moresco, F. and Cuniberti, G.},
      title={Hexacene generated on passivated silicon},
      journal={Nanoscale},
      year={2018},
      volume={10},
      number={26},
      pages={12582-12587},
      doi={10.1039/c8nr03422b},
      note={cited By 5},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049863961&doi=10.1039%2fc8nr03422b&partnerID=40&md5=b0203d0742a1ad90ba5f4ec5b4202d47},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela, 15782, Spain; Bremen Center for Computational Materials Science (BCCMS), Universität Bremen, Bremen, 28359, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01069, Germany},
      abstract={On-surface synthesis represents a successful strategy to obtain designed molecular structures on an ultra-clean metal substrate. While metal surfaces are known to favor adsorption, diffusion, and chemical bonding between molecular groups, on-surface synthesis on non-metallic substrates would allow the electrical decoupling of the resulting molecule from the surface, favoring application to electronics and spintronics. Here, we demonstrate the on-surface generation of hexacene by surface-assisted reduction on a H-passivated Si(001) surface. The reaction, observed by scanning tunneling microscopy and spectroscopy, is probably driven by the formation of Si-O complexes at dangling bond defects. Supported by density functional theory calculations, we investigate the interaction of hexacene with the passivated silicon surface, and with single silicon dangling bonds. © The Royal Society of Chemistry.},
      keywords={Chemical bonds; Dangling bonds; Density functional theory; Scanning tunneling microscopy; Silicon compounds; Substrates; Surface reactions; Synthesis (chemical), Chemical bondings; Electrical decoupling; Molecular groups; Non-metallic substrates; Scanning tunneling microscopy and spectroscopy; Si(001) surfaces; Silicon dangling bond; Surface generations, Passivation},
      correspondence_address1={Peña, D.; Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Spain},
      publisher={Royal Society of Chemistry},
      issn={20403364},
      pubmed_id={29938293},
      language={English},
      abbrev_source_title={Nanoscale},
      document_type={Article},
      source={Scopus},
      }

  • Self-Assembled Two-Dimensional Supramolecular Networks Characterized by Scanning Tunneling Microscopy and Spectroscopy in Air and under Vacuum
    • B. Naydenov, S. Torsney, A. S. Bonilla, M. El Garah, A. Ciesielski, A. Gualandi, L. Mengozzi, P. G. Cozzi, R. Gutierrez, P. Samorì, G. Cuniberti, J. J. Boland
    • Langmuir 34, 7698-7707 (2018)
    • DOI   Abstract  

      We combine ambient (air) and ultrahigh vacuum (UHV) scanning tunneling microscopy (STM) and spectroscopy (STS) investigations together with density functional theory (DFT) calculations to gain a subnanometer insight into the structure and dynamic of two-dimensional (2D) surface-supported molecular networks. The planar tetraferrocene-porphyrin molecules employed in this study undergo spontaneous self-assembly via the formation of hydrogen bonded networks at the gold substrate-solution interface. To mimic liquid phase ambient deposition conditions, film formation was accomplished in UHV by electro-spraying a solution of the molecule in chloroform onto an Au(111) substrate, thereby providing access to the full spectroscopic capabilities of STM that can be hardly attained under ambient conditions. We show that molecular assembly on Au (111) is identical in films prepared under the two different conditions, and in good agreement with the theoretical predictions. However, we observe the contrast found for a given STM bias condition to be different in ambient and UHV conditions despite the similarity of the structures, and we propose possible origins of the different imaging contrast. This approach could be valuable for the thorough characterization of surface systems that involve large molecules and are prepared mainly in ambient conditions. © 2018 American Chemical Society.

      @ARTICLE{Naydenov20187698,
      author={Naydenov, B. and Torsney, S. and Bonilla, A.S. and El Garah, M. and Ciesielski, A. and Gualandi, A. and Mengozzi, L. and Cozzi, P.G. and Gutierrez, R. and Samorì, P. and Cuniberti, G. and Boland, J.J.},
      title={Self-Assembled Two-Dimensional Supramolecular Networks Characterized by Scanning Tunneling Microscopy and Spectroscopy in Air and under Vacuum},
      journal={Langmuir},
      year={2018},
      volume={34},
      number={26},
      pages={7698-7707},
      doi={10.1021/acs.langmuir.8b01374},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048568384&doi=10.1021%2facs.langmuir.8b01374&partnerID=40&md5=8f599314ecd99ddf1eb6f76b5421e97c},
      affiliation={Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), School of Chemistry, Trinity College Dublin, I-Dublin-2, Ireland; Institute for Materials Sciences, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Université de Strasbourg, CNRS, ISIS, 8 alleé Gaspard Monge, Strasbourg, 67000, France; Dipartimento di Chimica G. Ciamician, Alma Mater Studiorum Università di Bologna, Via Selmi 2, Bologna, 40126, Italy; Dresden Center for Computational Materials Science (DCCMS), TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={We combine ambient (air) and ultrahigh vacuum (UHV) scanning tunneling microscopy (STM) and spectroscopy (STS) investigations together with density functional theory (DFT) calculations to gain a subnanometer insight into the structure and dynamic of two-dimensional (2D) surface-supported molecular networks. The planar tetraferrocene-porphyrin molecules employed in this study undergo spontaneous self-assembly via the formation of hydrogen bonded networks at the gold substrate-solution interface. To mimic liquid phase ambient deposition conditions, film formation was accomplished in UHV by electro-spraying a solution of the molecule in chloroform onto an Au(111) substrate, thereby providing access to the full spectroscopic capabilities of STM that can be hardly attained under ambient conditions. We show that molecular assembly on Au (111) is identical in films prepared under the two different conditions, and in good agreement with the theoretical predictions. However, we observe the contrast found for a given STM bias condition to be different in ambient and UHV conditions despite the similarity of the structures, and we propose possible origins of the different imaging contrast. This approach could be valuable for the thorough characterization of surface systems that involve large molecules and are prepared mainly in ambient conditions. © 2018 American Chemical Society.},
      keywords={Chlorine compounds; Density functional theory; Film preparation; Hydrogen bonds; Interfaces (materials); Molecules; Self assembly; Ultrahigh vacuum, 2D supramolecular networks; Au (111) substrates; Deposition conditions; Hydrogen bonded network; Molecular assembly; Porphyrin molecules; Structure and dynamics; Two Dimensional (2 D), Scanning tunneling microscopy},
      correspondence_address1={Boland, J.J.; Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Ireland; email: jbolnad@tcd.ie},
      publisher={American Chemical Society},
      issn={07437463},
      coden={LANGD},
      pubmed_id={29889539},
      language={English},
      abbrev_source_title={Langmuir},
      document_type={Article},
      source={Scopus},
      }

  • Pressure-induced dimerization and valence bond crystal formation in the Kitaev-Heisenberg magnet α-RuCl3
    • G. Bastien, G. Garbarino, R. Yadav, F. J. Martinez-Casado, R. Beltrán Rodríguez, Q. Stahl, M. Kusch, S. P. Limandri, R. Ray, P. Lampen-Kelley, D. G. Mandrus, S. E. Nagler, M. Roslova, A. Isaeva, T. Doert, L. Hozoi, A. U. B. Wolter, B. Büchner, J. Geck, J. Van Den Brink
    • Physical Review B 97, 241108 (2018)
    • DOI   Abstract  

      Magnetization and high-resolution x-ray diffraction measurements of the Kitaev-Heisenberg material α-RuCl3 reveal a pressure-induced crystallographic and magnetic phase transition at a hydrostatic pressure of p∼0.2 GPa. This structural transition into a triclinic phase is characterized by a very strong dimerization of the Ru-Ru bonds, accompanied by a collapse of the magnetic susceptibility. Ab initio quantum-chemistry calculations disclose a pressure-induced enhancement of the direct 4d-4d bonding on particular Ru-Ru links, causing a sharp increase of the antiferromagnetic exchange interactions. These combined experimental and computational data show that the Kitaev spin-liquid phase in α-RuCl3 strongly competes with the crystallization of spin singlets into a valence bond solid. © 2018 authors. Published by the American Physical Society.

      @ARTICLE{Bastien2018,
      author={Bastien, G. and Garbarino, G. and Yadav, R. and Martinez-Casado, F.J. and Beltrán Rodríguez, R. and Stahl, Q. and Kusch, M. and Limandri, S.P. and Ray, R. and Lampen-Kelley, P. and Mandrus, D.G. and Nagler, S.E. and Roslova, M. and Isaeva, A. and Doert, T. and Hozoi, L. and Wolter, A.U.B. and Büchner, B. and Geck, J. and Van Den Brink, J.},
      title={Pressure-induced dimerization and valence bond crystal formation in the Kitaev-Heisenberg magnet α-RuCl3},
      journal={Physical Review B},
      year={2018},
      volume={97},
      number={24},
      doi={10.1103/PhysRevB.97.241108},
      art_number={241108},
      note={cited By 63},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048701800&doi=10.1103%2fPhysRevB.97.241108&partnerID=40&md5=3acd9f0160e35f75e33170b9f61341c9},
      affiliation={Leibniz-Institut für Festkörper- und Werkstoffforschung (IFW) Dresden, Dresden, 01171, Germany; European Synchrotron Radiation Facility, Grenoble, 38043, France; Institut Laue-Langevin, Grenoble, 38042, France; Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC, Universidad de Zaragoza, Zaragoza, 50009, Spain; Institut für Festkörper- und Materialphysik, Technische Universität Dresden, Dresden, 01062, Germany; IFEG, CONICET, Ciudad Universitaria, Medina Allende s/n, Cordoba, 5000, Argentina; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States; Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, United States; Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States; Fakultät für Chemie und Lebensmittelchemie, Technische Universität Dresden, Dresden, 01062, Germany; Institut für Theoretische Physik, Technische Universität Dresden, Dresden, 01062, Germany; Department of Physics, Harvard University, Cambridge, MA 02138, United States},
      abstract={Magnetization and high-resolution x-ray diffraction measurements of the Kitaev-Heisenberg material α-RuCl3 reveal a pressure-induced crystallographic and magnetic phase transition at a hydrostatic pressure of p∼0.2 GPa. This structural transition into a triclinic phase is characterized by a very strong dimerization of the Ru-Ru bonds, accompanied by a collapse of the magnetic susceptibility. Ab initio quantum-chemistry calculations disclose a pressure-induced enhancement of the direct 4d-4d bonding on particular Ru-Ru links, causing a sharp increase of the antiferromagnetic exchange interactions. These combined experimental and computational data show that the Kitaev spin-liquid phase in α-RuCl3 strongly competes with the crystallization of spin singlets into a valence bond solid. © 2018 authors. Published by the American Physical Society.},
      publisher={American Physical Society},
      issn={24699950},
      language={English},
      abbrev_source_title={Phys. Rev. B},
      document_type={Article},
      source={Scopus},
      }

  • Lattice dynamics and metastability of fcc metals in the hcp structure and the crucial role of spin-orbit coupling in platinum
    • S. Schönecker, X. Li, M. Richter, L. Vitos
    • Physical Review B 97, 224305 (2018)
    • DOI   Abstract  

      We investigate the lattice dynamical properties of Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au in the nonequilibrium hcp structure by means of density-functional simulations, wherein spin-orbit coupling (SOC) was considered for Ir, Pt, and Au. The determined dynamical properties reveal that all eight elements possess a metastable hcp phase at zero temperature and pressure. The hcp Ni, Cu, Rh, Pd, and Au previously observed in nanostructures support this finding. We make evident that the inclusion of SOC is mandatory for an accurate description of the phonon dispersion relations and dynamical stability of hcp Pt. The underlying sensitivity of the interatomic force constants is ascribed to a SOC-induced splitting of degenerate band states accompanied by a pronounced reduction of electronic density of states at the Fermi level. To give further insight into the importance of SOC in Pt, we (i) focus on phase stability and examine a lattice transformation related to optical phonons in the hcp phase and (ii) focus on the generalized stacking fault energy (GSFE) of the fcc phase pertinent to crystal plasticity. We show that the intrinsic stable and unstable fault energies of the GSFE scale as in other common fcc metals, provided that the spin-orbit interaction is taken into account. © 2018 American Physical Society.

      @ARTICLE{Schönecker2018,
      author={Schönecker, S. and Li, X. and Richter, M. and Vitos, L.},
      title={Lattice dynamics and metastability of fcc metals in the hcp structure and the crucial role of spin-orbit coupling in platinum},
      journal={Physical Review B},
      year={2018},
      volume={97},
      number={22},
      doi={10.1103/PhysRevB.97.224305},
      art_number={224305},
      note={cited By 10},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048722613&doi=10.1103%2fPhysRevB.97.224305&partnerID=40&md5=85db9849587c59c4bd4b5cbb3da188f0},
      affiliation={Applied Materials Physics, Department of Materials Science and Engineering, KTH Royal Institute of Technology, Stockholm, SE-10044, Sweden; IFW Dresden, Dresden Center for Computational Materials Science, Dresden, D-01069, Germany; Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Box 516, Uppsala, SE-75120, Sweden; Research Institute for Solid State Physics and Optics, Wigner Research Center for Physics, P.O. Box 49, Budapest, H-1525, Hungary},
      abstract={We investigate the lattice dynamical properties of Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au in the nonequilibrium hcp structure by means of density-functional simulations, wherein spin-orbit coupling (SOC) was considered for Ir, Pt, and Au. The determined dynamical properties reveal that all eight elements possess a metastable hcp phase at zero temperature and pressure. The hcp Ni, Cu, Rh, Pd, and Au previously observed in nanostructures support this finding. We make evident that the inclusion of SOC is mandatory for an accurate description of the phonon dispersion relations and dynamical stability of hcp Pt. The underlying sensitivity of the interatomic force constants is ascribed to a SOC-induced splitting of degenerate band states accompanied by a pronounced reduction of electronic density of states at the Fermi level. To give further insight into the importance of SOC in Pt, we (i) focus on phase stability and examine a lattice transformation related to optical phonons in the hcp phase and (ii) focus on the generalized stacking fault energy (GSFE) of the fcc phase pertinent to crystal plasticity. We show that the intrinsic stable and unstable fault energies of the GSFE scale as in other common fcc metals, provided that the spin-orbit interaction is taken into account. © 2018 American Physical Society.},
      keywords={Electronic density of states; Gold; Iridium compounds; Lattice vibrations; Optical lattices; Phonons; Platinum; Spin dynamics; Stability, Density functionals; Dynamical properties; Dynamical stability; Generalized stacking fault energies; Lattice dynamical properties; Phonon dispersion relations; Spin orbit interactions; Spin-orbit couplings, Platinum compounds},
      publisher={American Physical Society},
      issn={24699950},
      language={English},
      abbrev_source_title={Phys. Rev. B},
      document_type={Article},
      source={Scopus},
      }

  • A Dual-Stimuli-Responsive Sodium-Bromine Battery with Ultrahigh Energy Density
    • F. Wang, H. Yang, J. Zhang, P. Zhang, G. Wang, X. Zhuang, G. Cuniberti, X. Feng
    • Advanced Materials 30, 1800028 (2018)
    • DOI   Abstract  

      Stimuli-responsive energy storage devices have emerged for the fast-growing popularity of intelligent electronics. However, all previously reported stimuli-responsive energy storage devices have rather low energy densities (<250 Wh kg–1) and single stimuli-response, which seriously limit their application scopes in intelligent electronics. Herein, a dual-stimuli-responsive sodium-bromine (Na//Br2) battery featuring ultrahigh energy density, electrochromic effect, and fast thermal response is demonstrated. Remarkably, the fabricated Na//Br2 battery exhibits a large operating voltage of 3.3 V and an energy density up to 760 Wh kg−1, which outperforms those for the state-of-the-art stimuli-responsive electrochemical energy storage devices. This work offers a promising approach for designing multi-stimuli-responsive and high-energy rechargeable batteries without sacrificing the electrochemical performance. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

      @ARTICLE{Wang2018,
      author={Wang, F. and Yang, H. and Zhang, J. and Zhang, P. and Wang, G. and Zhuang, X. and Cuniberti, G. and Feng, X.},
      title={A Dual-Stimuli-Responsive Sodium-Bromine Battery with Ultrahigh Energy Density},
      journal={Advanced Materials},
      year={2018},
      volume={30},
      number={23},
      doi={10.1002/adma.201800028},
      art_number={1800028},
      note={cited By 48},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85046107138&doi=10.1002%2fadma.201800028&partnerID=40&md5=abca260aaa2e14fba62098add75b4ab0},
      affiliation={Chair of Molecular Functional Materials, School of Science, Technische Universität Dresden, Mommsenstrasse 4, Dresden, 01069, Germany; Center for Advancing Electronics Dresden (cfaed), Technische Universität Dresden, Dresden, 01062, Germany; Institute for Materials Science and Max Bergmann Center of Biomaterials, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, 01062, Germany; The State Key Laboratory of Metal Matrix Composites & Shanghai Key Laboratory of Electrical Insulation and Thermal Ageing, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai, 200240, China},
      abstract={Stimuli-responsive energy storage devices have emerged for the fast-growing popularity of intelligent electronics. However, all previously reported stimuli-responsive energy storage devices have rather low energy densities (<250 Wh kg–1) and single stimuli-response, which seriously limit their application scopes in intelligent electronics. Herein, a dual-stimuli-responsive sodium-bromine (Na//Br2) battery featuring ultrahigh energy density, electrochromic effect, and fast thermal response is demonstrated. Remarkably, the fabricated Na//Br2 battery exhibits a large operating voltage of 3.3 V and an energy density up to 760 Wh kg−1, which outperforms those for the state-of-the-art stimuli-responsive electrochemical energy storage devices. This work offers a promising approach for designing multi-stimuli-responsive and high-energy rechargeable batteries without sacrificing the electrochemical performance. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim},
      author_keywords={electrochromic; high energy density; multi-functions; sodium-bromine battery; thermal response},
      keywords={Bromine; Electric energy storage; Electrochromism; Sodium, Electrochemical energy storage devices; Electrochemical performance; Electrochromic effect; Electrochromics; High energy densities; Intelligent electronics; Multi-functions; Thermal response, Secondary batteries},
      correspondence_address1={Zhuang, X.; Chair of Molecular Functional Materials, Mommsenstrasse 4, Germany; email: zhuang@sjtu.edu.cn},
      publisher={Wiley-VCH Verlag},
      issn={09359648},
      coden={ADVME},
      pubmed_id={29707829},
      language={English},
      abbrev_source_title={Adv Mater},
      document_type={Article},
      source={Scopus},
      }

  • Nematic liquid crystals on curved surfaces: A thin film limit
    • I. Nitschke, M. Nestler, S. Praetorius, H. Löwen, A. Voigt
    • Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, 20170686 (2018)
    • DOI   Abstract  

      We consider a thin film limit of a Landau-de Gennes Q-tensor model. In the limiting process, we observe a continuous transition where the normal and tangential parts of the Q-tensor decouple and various intrinsic and extrinsic contributions emerge. The main properties of the thin film model, like uniaxiality and parameter phase space, are preserved in the limiting process. For the derived surface Landau-de Gennes model, we consider an L2-gradient flow. The resulting tensor-valued surface partial differential equation is numerically solved to demonstrate realizations of the tight coupling of elastic and bulk free energy with geometric properties. © 2018 The Author(s) Published by the Royal Society. All rights reserved.

      @ARTICLE{Nitschke2018,
      author={Nitschke, I. and Nestler, M. and Praetorius, S. and Löwen, H. and Voigt, A.},
      title={Nematic liquid crystals on curved surfaces: A thin film limit},
      journal={Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences},
      year={2018},
      volume={474},
      number={2214},
      doi={10.1098/rspa.2017.0686},
      art_number={20170686},
      note={cited By 14},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049627191&doi=10.1098%2frspa.2017.0686&partnerID=40&md5=ad2e9e482e326a0d6298c82ca461a2e7},
      affiliation={Institut für Wissenschaftliches Rechnen, Technische Universität Dresden, Dresden, 01062, Germany; Institut für Theoretische Physik II - Soft Matter, Heinrich-HeineUniversität Düsseldorf, Düsseldorf, 40225, Germany; Dresden Center for Computational Materials Science (DCMS), Dresden, 01062, Germany},
      abstract={We consider a thin film limit of a Landau-de Gennes Q-tensor model. In the limiting process, we observe a continuous transition where the normal and tangential parts of the Q-tensor decouple and various intrinsic and extrinsic contributions emerge. The main properties of the thin film model, like uniaxiality and parameter phase space, are preserved in the limiting process. For the derived surface Landau-de Gennes model, we consider an L2-gradient flow. The resulting tensor-valued surface partial differential equation is numerically solved to demonstrate realizations of the tight coupling of elastic and bulk free energy with geometric properties. © 2018 The Author(s) Published by the Royal Society. All rights reserved.},
      author_keywords={Nematic liquid crystals; Surface equation; Thin film limit},
      keywords={Free energy; Phase space methods; Tensors; Thin films, Bulk free energy; Continuous transitions; Curved surfaces; Geometric properties; Landau-de-Gennes model; Limiting process; Surface equation; Thin film model, Nematic liquid crystals},
      correspondence_address1={Nitschke, I.; Institut für Wissenschaftliches Rechnen, Germany; email: ingo.nitschke@tu-dresden.de},
      publisher={Royal Society Publishing},
      issn={13645021},
      language={English},
      abbrev_source_title={Proc. R. Soc. A Math. Phys. Eng. Sci.},
      document_type={Article},
      source={Scopus},
      }

  • Projection and transfer operators in adaptive isogeometric analysis with hierarchical B-splines
    • P. Hennig, M. Ambati, L. De Lorenzis, M. Kästner
    • Computer Methods in Applied Mechanics and Engineering 334, 313-336 (2018)
    • DOI   Abstract  

      We present projection methods and transfer operations required for adaptive mesh refinement/coarsening in problems with internal variables. We extend the results of Hennig et al. 2016 on Bézier extraction of truncated hierarchical B-splines and its application to adaptive isogeometric analysis. It is shown that isogeometric analysis improves the performance of transfer operations as already the coarsest mesh represents the exact geometry and the hierarchical structure allows for quadrature free projection methods. We propose two different local least squares projection methods for field variables and compare them to existing global and semi-local versions. We discuss the application of two different transfer operators for internal variables. An alternative new operator inspired by superconvergent patch recovery is also proposed. The presented projection methods and transfer operations are tested in benchmark problems and applied to phase-field modelling of spinodal decomposition and brittle and ductile fracture. © 2018 Elsevier B.V.

      @ARTICLE{Hennig2018313,
      author={Hennig, P. and Ambati, M. and De Lorenzis, L. and Kästner, M.},
      title={Projection and transfer operators in adaptive isogeometric analysis with hierarchical B-splines},
      journal={Computer Methods in Applied Mechanics and Engineering},
      year={2018},
      volume={334},
      pages={313-336},
      doi={10.1016/j.cma.2018.01.017},
      note={cited By 31},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042377915&doi=10.1016%2fj.cma.2018.01.017&partnerID=40&md5=3cf0801e6785296a5aa4157f5f692010},
      affiliation={Institute of Solid Mechanics, TU Dresden, Dresden, 01062, Germany; Institute of Applied Mechanics, TU Braunschweig, Braunschweig, 38106, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={We present projection methods and transfer operations required for adaptive mesh refinement/coarsening in problems with internal variables. We extend the results of Hennig et al. 2016 on Bézier extraction of truncated hierarchical B-splines and its application to adaptive isogeometric analysis. It is shown that isogeometric analysis improves the performance of transfer operations as already the coarsest mesh represents the exact geometry and the hierarchical structure allows for quadrature free projection methods. We propose two different local least squares projection methods for field variables and compare them to existing global and semi-local versions. We discuss the application of two different transfer operators for internal variables. An alternative new operator inspired by superconvergent patch recovery is also proposed. The presented projection methods and transfer operations are tested in benchmark problems and applied to phase-field modelling of spinodal decomposition and brittle and ductile fracture. © 2018 Elsevier B.V.},
      author_keywords={Adaptivity; Coarsening; Isogeometric analysis; Phase-field modelling; Refinement; Truncated hierarchical B-splines},
      keywords={Brittle fracture; Coarsening; Ductile fracture; Interpolation; Mesh generation; Spinodal decomposition, Adaptivity; B splines; Isogeometric analysis; Phase field modelling; Refinement, Least squares approximations},
      correspondence_address1={Kästner, M.; Institute of Solid Mechanics, Germany; email: Markus.Kaestner@tu-dresden.de},
      publisher={Elsevier B.V.},
      issn={00457825},
      coden={CMMEC},
      language={English},
      abbrev_source_title={Comput. Methods Appl. Mech. Eng.},
      document_type={Article},
      source={Scopus},
      }

  • Defects at grain boundaries: A coarse-grained, three-dimensional description by the amplitude expansion of the phase-field crystal model
    • M. Salvalaglio, R. Backofen, K. R. Elder, A. Voigt
    • Physical Review Materials 2, 053804 (2018)
    • DOI   Abstract  

      We address a three-dimensional, coarse-grained description of dislocation networks at grain boundaries between rotated crystals. The so-called amplitude expansion of the phase-field crystal model is exploited with the aid of finite element method calculations. This approach allows for the description of microscopic features, such as dislocations, while simultaneously being able to describe length scales that are orders of magnitude larger than the lattice spacing. Moreover, it allows for the direct description of extended defects by means of a scalar order parameter. The versatility of this framework is shown by considering both fcc and bcc lattice symmetries and different rotation axes. First, the specific case of planar, twist grain boundaries is illustrated. The details of the method are reported and the consistency of the results with literature is discussed. Then, the dislocation networks forming at the interface between a spherical, rotated crystal embedded in an unrotated crystalline structure, are shown. Although explicitly accounting for dislocations which lead to an anisotropic shrinkage of the rotated grain, the extension of the spherical grain boundary is found to decrease linearly over time in agreement with the classical theory of grain growth and recent atomistic investigations. It is shown that the results obtained for a system with bcc symmetry agree very well with existing results, validating the methodology. Furthermore, fully original results are shown for fcc lattice symmetry, revealing the generality of the reported observations. © 2018 American Physical Society.

      @ARTICLE{Salvalaglio2018,
      author={Salvalaglio, M. and Backofen, R. and Elder, K.R. and Voigt, A.},
      title={Defects at grain boundaries: A coarse-grained, three-dimensional description by the amplitude expansion of the phase-field crystal model},
      journal={Physical Review Materials},
      year={2018},
      volume={2},
      number={5},
      doi={10.1103/PhysRevMaterials.2.053804},
      art_number={053804},
      note={cited By 17},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059634904&doi=10.1103%2fPhysRevMaterials.2.053804&partnerID=40&md5=8f1c3533eb8f2d54a1f7577610d57601},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Department of Physics, Oakland University, Rochester, MI 48309, United States; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={We address a three-dimensional, coarse-grained description of dislocation networks at grain boundaries between rotated crystals. The so-called amplitude expansion of the phase-field crystal model is exploited with the aid of finite element method calculations. This approach allows for the description of microscopic features, such as dislocations, while simultaneously being able to describe length scales that are orders of magnitude larger than the lattice spacing. Moreover, it allows for the direct description of extended defects by means of a scalar order parameter. The versatility of this framework is shown by considering both fcc and bcc lattice symmetries and different rotation axes. First, the specific case of planar, twist grain boundaries is illustrated. The details of the method are reported and the consistency of the results with literature is discussed. Then, the dislocation networks forming at the interface between a spherical, rotated crystal embedded in an unrotated crystalline structure, are shown. Although explicitly accounting for dislocations which lead to an anisotropic shrinkage of the rotated grain, the extension of the spherical grain boundary is found to decrease linearly over time in agreement with the classical theory of grain growth and recent atomistic investigations. It is shown that the results obtained for a system with bcc symmetry agree very well with existing results, validating the methodology. Furthermore, fully original results are shown for fcc lattice symmetry, revealing the generality of the reported observations. © 2018 American Physical Society.},
      keywords={Crystal lattices; Grain boundaries; Grain growth; Rotation, Anisotropic shrinkage; Coarse-grained description; Crystalline structure; Dislocation networks; Microscopic features; Orders of magnitude; Phase field crystal model; Twist grain boundary, Dislocations (crystals)},
      publisher={American Physical Society},
      issn={24759953},
      language={English},
      abbrev_source_title={Physic. Rev. Mat.},
      document_type={Article},
      source={Scopus},
      }

  • Active crystals on a sphere
    • S. Praetorius, A. Voigt, R. Wittkowski, H. Löwen
    • Physical Review E 97, 052615 (2018)
    • DOI   Abstract  

      Two-dimensional crystals on curved manifolds exhibit nontrivial defect structures. Here we consider “active crystals” on a sphere, which are composed of self-propelled colloidal particles. Our work is based on a phase-field-crystal-type model that involves a density and a polarization field on the sphere. Depending on the strength of the self-propulsion, three different types of crystals are found: a static crystal, a self-spinning “vortex-vortex” crystal containing two vortical poles of the local velocity, and a self-translating “source-sink” crystal with a source pole where crystallization occurs and a sink pole where the active crystal melts. These different crystalline states as well as their defects are studied theoretically here and can in principle be confirmed in experiments. © 2018 American Physical Society.

      @ARTICLE{Praetorius2018,
      author={Praetorius, S. and Voigt, A. and Wittkowski, R. and Löwen, H.},
      title={Active crystals on a sphere},
      journal={Physical Review E},
      year={2018},
      volume={97},
      number={5},
      doi={10.1103/PhysRevE.97.052615},
      art_number={052615},
      note={cited By 33},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047780948&doi=10.1103%2fPhysRevE.97.052615&partnerID=40&md5=0c6f195cfe8ea23c8198130b1ed0c7c7},
      affiliation={Institute for Scientific Computing, Technische Universität Dresden, Dresden, D-01062, Germany; Dresden Center for Computational Materials Science (DCMS), Dresden, D-01062, Germany; Center for Systems Biology Dresden (CSBD), Dresden, D-01307, Germany; Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Münster, D-48149, Germany; Center for Nonlinear Science (CeNoS), Westfälische Wilhelms-Universität Münster, Münster, D-48149, Germany; Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, D-40225, Germany},
      abstract={Two-dimensional crystals on curved manifolds exhibit nontrivial defect structures. Here we consider "active crystals" on a sphere, which are composed of self-propelled colloidal particles. Our work is based on a phase-field-crystal-type model that involves a density and a polarization field on the sphere. Depending on the strength of the self-propulsion, three different types of crystals are found: a static crystal, a self-spinning "vortex-vortex" crystal containing two vortical poles of the local velocity, and a self-translating "source-sink" crystal with a source pole where crystallization occurs and a sink pole where the active crystal melts. These different crystalline states as well as their defects are studied theoretically here and can in principle be confirmed in experiments. © 2018 American Physical Society.},
      keywords={Crystalline materials; Defects; Poles; Vortex flow, Colloidal particle; Crystal melt; Crystalline state; Local velocity; Phase-field crystals; Polarization field; Self propulsion; Two-dimensional crystals, Spheres, article; crystallization; language; polarization},
      publisher={American Physical Society},
      issn={24700045},
      pubmed_id={29906962},
      language={English},
      abbrev_source_title={Phys. Rev. E},
      document_type={Article},
      source={Scopus},
      }

  • Insight into doping efficiency of organic semiconductors from the analysis of the density of states in n-doped
    • C. Gaul, S. Hutsch, M. Schwarze, K. S. Schellhammer, F. Bussolotti, S. Kera, G. Cuniberti, K. Leo, F. Ortmann
    • Nature Materials 17, 439-444 (2018)
    • DOI   Abstract  

      Doping plays a crucial role in semiconductor physics, with n-doping being controlled by the ionization energy of the impurity relative to the conduction band edge. In organic semiconductors, efficient doping is dominated by various effects that are currently not well understood. Here, we simulate and experimentally measure, with direct and inverse photoemission spectroscopy, the density of states and the Fermi level position of the prototypical materials C60 and zinc phthalocyanine n-doped with highly efficient benzimidazoline radicals (2-Cyc-DMBI). We study the role of doping-induced gap states, and, in particular, of the difference Δ 1 between the electron affinity of the undoped material and the ionization potential of its doped counterpart. We show that this parameter is critical for the generation of free carriers and influences the conductivity of the doped films. Tuning of Δ 1 may provide alternative strategies to optimize the electronic properties of organic semiconductors. © 2018 The Author(s).

      @ARTICLE{Gaul2018439,
      author={Gaul, C. and Hutsch, S. and Schwarze, M. and Schellhammer, K.S. and Bussolotti, F. and Kera, S. and Cuniberti, G. and Leo, K. and Ortmann, F.},
      title={Insight into doping efficiency of organic semiconductors from the analysis of the density of states in n-doped},
      journal={Nature Materials},
      year={2018},
      volume={17},
      number={5},
      pages={439-444},
      doi={10.1038/s41563-018-0030-8},
      note={cited By 79},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042545903&doi=10.1038%2fs41563-018-0030-8&partnerID=40&md5=edeeb14001c923ffbdac1dcd2f0c7f72},
      affiliation={Center for Advancing Electronics Dresden, Dresden Center for Computational Materials Science, Technische Universität Dresden, Dresden, Germany; Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP), Institute for Applied Physics, Technische Universität Dresden, Dresden, Germany; Institute for Materials Science, Max Bergmann Center for Biomaterials, Technische Universität Dresden, Dresden, Germany; Institute for Molecular Science, Department of Photo-Molecular Science, Myodaiji, Okazaki, Japan; Institute of Materials Research and Engineering, Agency of Science, Technology and Research (A STAR), Singapore, Singapore},
      abstract={Doping plays a crucial role in semiconductor physics, with n-doping being controlled by the ionization energy of the impurity relative to the conduction band edge. In organic semiconductors, efficient doping is dominated by various effects that are currently not well understood. Here, we simulate and experimentally measure, with direct and inverse photoemission spectroscopy, the density of states and the Fermi level position of the prototypical materials C60 and zinc phthalocyanine n-doped with highly efficient benzimidazoline radicals (2-Cyc-DMBI). We study the role of doping-induced gap states, and, in particular, of the difference Δ 1 between the electron affinity of the undoped material and the ionization potential of its doped counterpart. We show that this parameter is critical for the generation of free carriers and influences the conductivity of the doped films. Tuning of Δ 1 may provide alternative strategies to optimize the electronic properties of organic semiconductors. © 2018 The Author(s).},
      keywords={Doping (additives); Electron affinity; Electronic properties; Ionization; Ionization potential; Photoelectron spectroscopy; Zinc compounds, Conduction band edge; Density of state; Doping efficiency; Induced gap state; Inverse photoemission spectroscopy; Semiconductor physics; Undoped material; Zinc phthalocyanines, Semiconductor doping},
      correspondence_address1={Ortmann, F.; Center for Advancing Electronics Dresden, Germany; email: frank.ortmann@tu-dresden.de},
      publisher={Nature Publishing Group},
      issn={14761122},
      coden={NMAAC},
      pubmed_id={29483635},
      language={English},
      abbrev_source_title={Nat. Mater.},
      document_type={Article},
      source={Scopus},
      }

  • Chirality-Dependent Electron Spin Filtering by Molecular Monolayers of Helicenes
    • M. Kettner, V. V. Maslyuk, D. Nürenberg, J. Seibel, R. Gutierrez, G. Cuniberti, K. -H. Ernst, H. Zacharias
    • Journal of Physical Chemistry Letters 9, 2025-2030 (2018)
    • DOI   Abstract  

      The interaction of low-energy photoelectrons with well-ordered monolayers of enantiopure helical heptahelicene molecules adsorbed on metal surfaces leads to a preferential transmission of one longitudinally polarized spin component, which is strongly coupled to the helical sense of the molecules. Heptahelicene, composed of only carbon and hydrogen atoms, exhibits only a single helical turn but shows excess in longitudinal spin polarization of about PZ = 6 to 8% after transmission of initially balanced left- and right-handed spin polarized electrons. Insight into the electronic structure, that is, the projected density of states, and the spin-dependent electron scattering in the helicene molecule is gained by using spin-resolved density functional theory calculations and a model Hamiltonian approach, respectively. Our results support the semiclassical picture of electronic transport along a helical pathway under the influence of spin-orbit coupling induced by the electrostatic molecular potential. © 2018 American Chemical Society.

      @ARTICLE{Kettner20182025,
      author={Kettner, M. and Maslyuk, V.V. and Nürenberg, D. and Seibel, J. and Gutierrez, R. and Cuniberti, G. and Ernst, K.-H. and Zacharias, H.},
      title={Chirality-Dependent Electron Spin Filtering by Molecular Monolayers of Helicenes},
      journal={Journal of Physical Chemistry Letters},
      year={2018},
      volume={9},
      number={8},
      pages={2025-2030},
      doi={10.1021/acs.jpclett.8b00208},
      note={cited By 99},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045762554&doi=10.1021%2facs.jpclett.8b00208&partnerID=40&md5=ce7d003a2ba807314e36f15b73532194},
      affiliation={Center for Soft Nanoscience, Physikalisches Institut, University of Münster, Münster, 48149, Germany; Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, 8600, Switzerland; Dresden Center for Computational Materials Science, Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Department of Chemistry, University of Zurich, Zürich, 8057, Switzerland},
      abstract={The interaction of low-energy photoelectrons with well-ordered monolayers of enantiopure helical heptahelicene molecules adsorbed on metal surfaces leads to a preferential transmission of one longitudinally polarized spin component, which is strongly coupled to the helical sense of the molecules. Heptahelicene, composed of only carbon and hydrogen atoms, exhibits only a single helical turn but shows excess in longitudinal spin polarization of about PZ = 6 to 8% after transmission of initially balanced left- and right-handed spin polarized electrons. Insight into the electronic structure, that is, the projected density of states, and the spin-dependent electron scattering in the helicene molecule is gained by using spin-resolved density functional theory calculations and a model Hamiltonian approach, respectively. Our results support the semiclassical picture of electronic transport along a helical pathway under the influence of spin-orbit coupling induced by the electrostatic molecular potential. © 2018 American Chemical Society.},
      keywords={Atoms; Density functional theory; Electron scattering; Electronic structure; Hamiltonians; Magnetic moments; Molecules; Monolayers; Spin polarization; Stereochemistry, Carbon and hydrogens; Electronic transport; Low-energy photoelectrons; Molecular monolayer; Molecular potential; Projected density of state; Spin-orbit couplings; Spin-polarized electrons, Electrospinning},
      correspondence_address1={Zacharias, H.; Center for Soft Nanoscience, Germany; email: hzach@uni-muenster.de},
      publisher={American Chemical Society},
      issn={19487185},
      pubmed_id={29618210},
      language={English},
      abbrev_source_title={J. Phys. Chem. Lett.},
      document_type={Article},
      source={Scopus},
      }

  • Solid-state dewetting of single-crystal silicon on insulator: effect of annealing temperature and patch size
    • M. Abbarchi, M. Naffouti, M. Lodari, M. Salvalaglio, R. Backofen, T. Bottein, A. Voigt, T. David, J. -B. Claude, M. Bouabdellaoui, A. Benkouider, I. Fraj, L. Favre, A. Ronda, I. Berbezier, D. Grosso, M. Bollani
    • Microelectronic Engineering 190, 1-6 (2018)
    • DOI   Abstract  

      We address the solid state dewetting of ultra-thin and ultra-large patches of monocrystalline silicon on insulator. We show that the underlying instability of the thin Si film under annealing can be perfectly controlled to form monocrystalline, complex nanoarchitectures extending over several microns. These complex patterns are obtained guiding the dewetting fronts by etching ad-hoc patches prior to annealing. They can be reproduced over hundreds of repetitions extending over hundreds of microns. We discuss the effect of annealing temperature and patch size on the stability of the final result of dewetting showing that for simple patches (e.g. simple squares) the final outcome is stable and well reproducible at 720 °C and for ~ 1 μm square size. Finally, we demonstrate that introducing additional features within squared patches (e.g. a hole within a square) stabilises the dewetting dynamic providing perfectly reproducible complex nanoarchitectures of 5 μm size. © 2018 Elsevier B.V.

      @ARTICLE{Abbarchi20181,
      author={Abbarchi, M. and Naffouti, M. and Lodari, M. and Salvalaglio, M. and Backofen, R. and Bottein, T. and Voigt, A. and David, T. and Claude, J.-B. and Bouabdellaoui, M. and Benkouider, A. and Fraj, I. and Favre, L. and Ronda, A. and Berbezier, I. and Grosso, D. and Bollani, M.},
      title={Solid-state dewetting of single-crystal silicon on insulator: effect of annealing temperature and patch size},
      journal={Microelectronic Engineering},
      year={2018},
      volume={190},
      pages={1-6},
      doi={10.1016/j.mee.2018.01.002},
      note={cited By 7},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039982935&doi=10.1016%2fj.mee.2018.01.002&partnerID=40&md5=5d02262dae4c013a0159ba8861787e12},
      affiliation={Aix Marseille Université CNRS Université de Toulon IM2NP UMR 7334, Marseille, 13397, France; Laboratoire de Micro-optoélectronique et Nanostructures Faculté des Sciences de Monastir Université de Monastir, Monastir, 5019, Tunisia; Istituto di Fotonica e Nanotecnologie Consiglio Nazionale delle Ricerche (IFN-CNR), L-NESS laboratory, via Anzani 42, Como, 22100, Italy; Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany},
      abstract={We address the solid state dewetting of ultra-thin and ultra-large patches of monocrystalline silicon on insulator. We show that the underlying instability of the thin Si film under annealing can be perfectly controlled to form monocrystalline, complex nanoarchitectures extending over several microns. These complex patterns are obtained guiding the dewetting fronts by etching ad-hoc patches prior to annealing. They can be reproduced over hundreds of repetitions extending over hundreds of microns. We discuss the effect of annealing temperature and patch size on the stability of the final result of dewetting showing that for simple patches (e.g. simple squares) the final outcome is stable and well reproducible at 720 °C and for ~ 1 μm square size. Finally, we demonstrate that introducing additional features within squared patches (e.g. a hole within a square) stabilises the dewetting dynamic providing perfectly reproducible complex nanoarchitectures of 5 μm size. © 2018 Elsevier B.V.},
      author_keywords={Nano-patterning; Solid-state dewetting; Ultra-thin silicon on insulator},
      keywords={Annealing; Silicon; Silicon on insulator technology; Silicon wafers; Single crystals, Complex pattern; De-wetting; Effect of annealing; Monocrystalline; Nanoarchitectures; NanoPatterning; Single crystal silicon; Ultrathin silicon, Monocrystalline silicon},
      correspondence_address1={Bollani, M.; Istituto di Fotonica e Nanotecnologie Consiglio Nazionale delle Ricerche (IFN-CNR), via Anzani 42, Italy; email: monica.bollani@ifn.cnr.it},
      publisher={Elsevier B.V.},
      issn={01679317},
      coden={MIENE},
      language={English},
      abbrev_source_title={Microelectron Eng},
      document_type={Article},
      source={Scopus},
      }

  • Bioinspired thermoresponsive nanoscaled coatings: Tailor-made polymer brushes with bioconjugated arginine-glycine-aspartic acid-peptides
    • U. König, E. Psarra, O. Guskova, E. Bittrich, K. -J. Eichhorn, M. Müller, P. B. Welzel, M. Stamm, P. Uhlmann
    • Biointerphases 13, 021002 (2018)
    • DOI   Abstract  

      The development of bioengineered surface coatings with stimuli-responsive properties is beneficial for a number of biomedical applications. Environmentally responsive and switchable polymer brush systems have a great potential to create such smart biointerfaces. This study focuses on the bioconjugation of cell-instructive peptides, containing the arginine-glycine-aspartic acid tripeptide sequence (RGD motif), onto well-defined polymer brush films. Herein, the highly tailored end-grafted homo polymer brushes are either composed of the polyelectrolyte poly(acrylic) acid (PAA), providing the reactive carboxyl functionalities, or of the temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm). Of particular interest is the preparation of grafted-to binary brushes using both polymers and their subsequent conversion to RGD-biofunctionalized PNIPAAm-PAA binary brushes by a carbodiimide conjugation method. The bioconjugation process of two linear RGD-peptides Gly-Arg-Gly-Asp-Ser and Gly-Arg-Gly-Asp-Ser-Pro-Lys and one cyclic RGD-peptide cyclo(Arg-Gly-Asp-D-Tyr-Lys) is comparatively investigated by complementary analysis methods. Both techniques, in situ attenuated total reflectance Fourier transform infrared spectroscopy measurements and the in situ spectroscopic ellipsometric analysis, describe changes of the brush surface properties due to biofunctionalization. Besides, the bound RGD-peptide amount is quantitatively evaluated by ellipsometry in comparison to high performance liquid chromatography analysis data. Additionally, molecular dynamic simulations of the RGD-peptides themselves allow a better understanding of the bioconjugation process depending on the peptide properties. The significant influence on the bioconjugation result can be derived, on the one hand, of the polymer brush composition, especially from the PNIPAAm content, and, on the other hand, of the peptide dimension and its reactivity. © 2018 Author(s).

      @ARTICLE{König2018,
      author={König, U. and Psarra, E. and Guskova, O. and Bittrich, E. and Eichhorn, K.-J. and Müller, M. and Welzel, P.B. and Stamm, M. and Uhlmann, P.},
      title={Bioinspired thermoresponsive nanoscaled coatings: Tailor-made polymer brushes with bioconjugated arginine-glycine-aspartic acid-peptides},
      journal={Biointerphases},
      year={2018},
      volume={13},
      number={2},
      doi={10.1116/1.5020129},
      art_number={021002},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047332792&doi=10.1116%2f1.5020129&partnerID=40&md5=8e2e7e0559c0fe0c3924fce79a7b2c77},
      affiliation={Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, 01069, Germany; Physical Chemistry of Polymeric Materials, Department of Chemistry, Faculty of Science, Technische Universität Dresden, Bergstrasse 66, Dresden, 01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, 01062, Germany; Department of Chemistry, Hamilton Hall, University of Nebraska-Lincoln, 639 N 12th Street, Lincoln, NE 68588, United States},
      abstract={The development of bioengineered surface coatings with stimuli-responsive properties is beneficial for a number of biomedical applications. Environmentally responsive and switchable polymer brush systems have a great potential to create such smart biointerfaces. This study focuses on the bioconjugation of cell-instructive peptides, containing the arginine-glycine-aspartic acid tripeptide sequence (RGD motif), onto well-defined polymer brush films. Herein, the highly tailored end-grafted homo polymer brushes are either composed of the polyelectrolyte poly(acrylic) acid (PAA), providing the reactive carboxyl functionalities, or of the temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm). Of particular interest is the preparation of grafted-to binary brushes using both polymers and their subsequent conversion to RGD-biofunctionalized PNIPAAm-PAA binary brushes by a carbodiimide conjugation method. The bioconjugation process of two linear RGD-peptides Gly-Arg-Gly-Asp-Ser and Gly-Arg-Gly-Asp-Ser-Pro-Lys and one cyclic RGD-peptide cyclo(Arg-Gly-Asp-D-Tyr-Lys) is comparatively investigated by complementary analysis methods. Both techniques, in situ attenuated total reflectance Fourier transform infrared spectroscopy measurements and the in situ spectroscopic ellipsometric analysis, describe changes of the brush surface properties due to biofunctionalization. Besides, the bound RGD-peptide amount is quantitatively evaluated by ellipsometry in comparison to high performance liquid chromatography analysis data. Additionally, molecular dynamic simulations of the RGD-peptides themselves allow a better understanding of the bioconjugation process depending on the peptide properties. The significant influence on the bioconjugation result can be derived, on the one hand, of the polymer brush composition, especially from the PNIPAAm content, and, on the other hand, of the peptide dimension and its reactivity. © 2018 Author(s).},
      keywords={Acrylic monomers; Amides; Arginine; Bioinformatics; Chlorine containing polymers; Dendrimers; Ellipsometry; Fourier transform infrared spectroscopy; Grafting (chemical); High performance liquid chromatography; Medical applications; Molecular dynamics; Peptides; Polyelectrolytes; Polymer films; Spectroscopic analysis, Arginine-glycine-aspartic acids; Attenuated total reflectance Fourier transform infrared spectroscopy; Biomedical applications; Complementary analysis; Ellipsometric analysis; Poly-n-isopropyl acrylamide; Stimuli-responsive properties; Temperature-responsive, Plastic coatings, acrylic acid resin; biocompatible coated material; biomimetic material; carbopol 940; nanomaterial; peptide; poly-N-isopropylacrylamide; protein binding, binding site; bioengineering; chemistry; high performance liquid chromatography; metabolism; molecular dynamics; procedures; spectroscopy; surface property, Acrylic Resins; Binding Sites; Bioengineering; Biomimetic Materials; Chromatography, High Pressure Liquid; Coated Materials, Biocompatible; Molecular Dynamics Simulation; Nanostructures; Peptides; Protein Binding; Spectrum Analysis; Surface Properties},
      publisher={American Institute of Physics Inc.},
      issn={19348630},
      pubmed_id={29776313},
      language={English},
      abbrev_source_title={Biointerphases},
      document_type={Article},
      source={Scopus},
      }

  • Effect of magnetic zigzag edges in graphene-like nanoribbons on the thermoelectric power factor
    • S. Krompiewski, G. Cuniberti
    • Acta Physica Polonica A 133, 535-537 (2018)
    • DOI   Abstract  

      This study shows that magnetic edge states of graphene-like nanoribbons enhance effectively the thermoelectric performance. This is due to the antiparallel alignment of magnetic moments on opposite zigzag edges and the confinement effect, which jointly lead to the appearance of a gap in the electronic energy spectrum. Consequently, the Seebeck coefficient as well as the thermoelectric power factor get strongly enhanced (with respect to other alignment cases) at room temperature and energies not far away from the charge neutrality point. Moreover the corresponding figure of merit (ZT) is also improved as a result of the reduced electronic thermal conductance. © 2018 Polish Academy of Sciences. All rights reserved.

      @ARTICLE{Krompiewski2018535,
      author={Krompiewski, S. and Cuniberti, G.},
      title={Effect of magnetic zigzag edges in graphene-like nanoribbons on the thermoelectric power factor},
      journal={Acta Physica Polonica A},
      year={2018},
      volume={133},
      number={3},
      pages={535-537},
      doi={10.12693/APhysPolA.133.535},
      note={cited By 0},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85045139896&doi=10.12693%2fAPhysPolA.133.535&partnerID=40&md5=7e0ee619c5fb404449538840b3bcda65},
      affiliation={Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, Poznań, 60-179, Poland; Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany},
      abstract={This study shows that magnetic edge states of graphene-like nanoribbons enhance effectively the thermoelectric performance. This is due to the antiparallel alignment of magnetic moments on opposite zigzag edges and the confinement effect, which jointly lead to the appearance of a gap in the electronic energy spectrum. Consequently, the Seebeck coefficient as well as the thermoelectric power factor get strongly enhanced (with respect to other alignment cases) at room temperature and energies not far away from the charge neutrality point. Moreover the corresponding figure of merit (ZT) is also improved as a result of the reduced electronic thermal conductance. © 2018 Polish Academy of Sciences. All rights reserved.},
      keywords={Graphene; Magnetic moments; Nanoribbons; Thermoelectric power; Thermoelectricity, Antiparallel alignment; Charge neutrality; Confinement effects; Electronic energy spectra; Figure of merits; Thermal conductance; Thermoelectric performance; Thermoelectric power factors, Electric power factor},
      correspondence_address1={Krompiewski, S.; Institute of Molecular Physics, M. Smoluchowskiego 17, Poland; email: stefan@ifmpan.poznan.pl},
      publisher={Polish Academy of Sciences},
      issn={05874246},
      coden={ATPLB},
      language={English},
      abbrev_source_title={Acta Phys Pol A},
      document_type={Conference Paper},
      source={Scopus},
      }

  • Unimolecular Logic Gate with Classical Input by Single Gold Atoms
    • D. Skidin, O. Faizy, J. Krüger, F. Eisenhut, A. Jancarik, K. -H. Nguyen, G. Cuniberti, A. Gourdon, F. Moresco, C. Joachim
    • ACS Nano 12, 1139-1145 (2018)
    • DOI   Abstract  

      By a combination of solution and on-surface chemistry, we synthesized an asymmetric starphene molecule with two long anthracenyl input branches and a short naphthyl output branch on the Au(111) surface. Starting from this molecule, we could demonstrate the working principle of a single molecule NAND logic gate by selectively contacting single gold atoms by atomic manipulation to the longer branches of the molecule. The logical input “1” (“0”) is defined by the interaction (noninteraction) of a gold atom with one of the input branches. The output is measured by scanning tunneling spectroscopy following the shift in energy of the electronic tunneling resonances at the end of the short branch of the molecule. © 2017 American Chemical Society.

      @ARTICLE{Skidin20181139,
      author={Skidin, D. and Faizy, O. and Krüger, J. and Eisenhut, F. and Jancarik, A. and Nguyen, K.-H. and Cuniberti, G. and Gourdon, A. and Moresco, F. and Joachim, C.},
      title={Unimolecular Logic Gate with Classical Input by Single Gold Atoms},
      journal={ACS Nano},
      year={2018},
      volume={12},
      number={2},
      pages={1139-1145},
      doi={10.1021/acsnano.7b06650},
      note={cited By 18},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042649463&doi=10.1021%2facsnano.7b06650&partnerID=40&md5=cb45de533af2bb049d0364b8f29b0390},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01069, Germany; GNS and MANA Satellite, CEMES, CNRS, 29 Rue J. Marvig, Toulouse, Cedex, 31055, France; Laboratoire de Physique Théorique, IRSAMC, Université de Toulouse, CNRS, UPS, Toulouse, Cedex, 31055, France; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01069, Germany; School of Nano Science, Institute for Research in Fundamental Sciences (IPM), Tehran, 19395-5531, Iran},
      abstract={By a combination of solution and on-surface chemistry, we synthesized an asymmetric starphene molecule with two long anthracenyl input branches and a short naphthyl output branch on the Au(111) surface. Starting from this molecule, we could demonstrate the working principle of a single molecule NAND logic gate by selectively contacting single gold atoms by atomic manipulation to the longer branches of the molecule. The logical input "1" ("0") is defined by the interaction (noninteraction) of a gold atom with one of the input branches. The output is measured by scanning tunneling spectroscopy following the shift in energy of the electronic tunneling resonances at the end of the short branch of the molecule. © 2017 American Chemical Society.},
      author_keywords={asymmetric starphene; molecular logic gate; on-surface synthesis; quantum Hamiltonian computing (QHC); scanning tunneling microscopy (STM)},
      keywords={Atoms; Computation theory; Computer circuits; Gold; Logic gates; Molecules; Quantum optics; Scanning tunneling microscopy; Surface chemistry; Synthesis (chemical), asymmetric starphene; Atomic manipulation; Au(111) surfaces; Electronic tunneling; Molecular logic gates; Quantum Hamiltonians; Scanning tunneling spectroscopy; Single molecule, Logic Synthesis},
      correspondence_address1={Moresco, F.; Institute for Materials Science, Germany; email: francesca.moresco@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19360851},
      pubmed_id={29266928},
      language={English},
      abbrev_source_title={ACS Nano},
      document_type={Article},
      source={Scopus},
      }

  • DFT study of interaction of additives with Cu(111) surface relevant to Cu electrodeposition
    • A. Dianat, H. Yang, M. Bobeth, G. Cuniberti
    • Journal of Applied Electrochemistry 48, 211-219 (2018)
    • DOI   Abstract  

      Abstract: The interaction of additives and ions with the copper surface plays a crucial role in the copper electroplating process. In this work, the interaction of the additives polyethylene glycol (PEG) and bis(3-sulfopropyl)-disulfide (SPS) as well as of chloride with the Cu(111) surface is considered within the framework of density functional theory. In the presence of water, the adsorption energy of chloride diminishes by about 1 eV compared to the case in vacuum. The activation barrier for chloride desorption was found to be 0.8 eV. Simulations of the deposition of copper atoms on a Cl-covered copper surface revealed that Cl atoms are always displaced to the surface. Calculations of adsorption energies of additives in vacuum indicated that the accelerator molecule SPS is bound stronger to Cu(111) than the suppressor molecule PEG. A comparatively strong adsorption of additives was found on a copper surface covered with a Cl–Cu mixed layer. Investigation of the dynamics of additives on Cu(111) by means of first principles molecular dynamics revealed an occasional spontaneous decomposition of an SPS molecule into two MPS molecules. Graphical Abstract: [Figure not available: see fulltext.]. © 2018, Springer Science+Business Media B.V., part of Springer Nature.

      @ARTICLE{Dianat2018211,
      author={Dianat, A. and Yang, H. and Bobeth, M. and Cuniberti, G.},
      title={DFT study of interaction of additives with Cu(111) surface relevant to Cu electrodeposition},
      journal={Journal of Applied Electrochemistry},
      year={2018},
      volume={48},
      number={2},
      pages={211-219},
      doi={10.1007/s10800-018-1150-1},
      note={cited By 13},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040773817&doi=10.1007%2fs10800-018-1150-1&partnerID=40&md5=d255dd54ddfe53f1425a2616ee862c69},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={Abstract: The interaction of additives and ions with the copper surface plays a crucial role in the copper electroplating process. In this work, the interaction of the additives polyethylene glycol (PEG) and bis(3-sulfopropyl)-disulfide (SPS) as well as of chloride with the Cu(111) surface is considered within the framework of density functional theory. In the presence of water, the adsorption energy of chloride diminishes by about 1 eV compared to the case in vacuum. The activation barrier for chloride desorption was found to be 0.8 eV. Simulations of the deposition of copper atoms on a Cl-covered copper surface revealed that Cl atoms are always displaced to the surface. Calculations of adsorption energies of additives in vacuum indicated that the accelerator molecule SPS is bound stronger to Cu(111) than the suppressor molecule PEG. A comparatively strong adsorption of additives was found on a copper surface covered with a Cl–Cu mixed layer. Investigation of the dynamics of additives on Cu(111) by means of first principles molecular dynamics revealed an occasional spontaneous decomposition of an SPS molecule into two MPS molecules. Graphical Abstract: [Figure not available: see fulltext.]. © 2018, Springer Science+Business Media B.V., part of Springer Nature.},
      author_keywords={Ab initio calculation; Additives; Adsorption energy; Copper electrodeposition; Damascene metallization},
      keywords={Additives; Adsorption; Calculations; Chlorine compounds; Copper; Density functional theory; Electrodeposition; Electrodes; Molecular dynamics; Molecules; Sulfur compounds, Ab initio calculations; Activation barriers; Adsorption energies; Bis(3-sulfopropyl) disulfide; Copper electrodeposition; Copper electroplating; Cu electrodepositions; First principles molecular dynamics, Copper compounds},
      correspondence_address1={Dianat, A.; Institute for Materials Science and Max Bergmann Center of Biomaterials, Germany; email: adianat@nano.tu-dresden.de},
      publisher={Springer Netherlands},
      issn={0021891X},
      coden={JAELB},
      language={English},
      abbrev_source_title={J Appl Electrochem},
      document_type={Article},
      source={Scopus},
      }

  • First-Principle-Based Phonon Transport Properties of Nanoscale Graphene Grain Boundaries
    • L. M. Sandonas, H. Sevinçli, R. Gutierrez, G. Cuniberti
    • Advanced Science 5, 1700365 (2018)
    • DOI   Abstract  

      The integrity of phonon transport properties of large graphene (linear and curved) grain boundaries (GBs) is investigated under the influence of structural and dynamical disorder. To do this, density functional tight-binding (DFTB) method is combined with atomistic Green’s function technique. The results show that curved GBs have lower thermal conductance than linear GBs. Its magnitude depends on the length of the curvature and out-of-plane structural distortions at the boundary, having stronger influence the latter one. Moreover, it is found that by increasing the defects at the boundary, the transport properties can strongly be reduced in comparison to the effect produced by heating up the boundary region. This is due to the large reduction of the phonon transmission for in-plane and out-of-plane vibrational modes after increasing the structural disorder in the GBs. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

      @ARTICLE{Sandonas2018,
      author={Sandonas, L.M. and Sevinçli, H. and Gutierrez, R. and Cuniberti, G.},
      title={First-Principle-Based Phonon Transport Properties of Nanoscale Graphene Grain Boundaries},
      journal={Advanced Science},
      year={2018},
      volume={5},
      number={2},
      doi={10.1002/advs.201700365},
      art_number={1700365},
      note={cited By 17},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040521258&doi=10.1002%2fadvs.201700365&partnerID=40&md5=35f818b4334fccbc1e2e51683255e9b7},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany; Department of Materials Science and Engineering, Izmir Institute of Technology, Izmir, Urla, 35430, Turkey; ICTP-ECAR Eurasian Centre for Advanced Research, Izmir Institute of Technology, Izmir, Urla, 35430, Turkey; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany},
      abstract={The integrity of phonon transport properties of large graphene (linear and curved) grain boundaries (GBs) is investigated under the influence of structural and dynamical disorder. To do this, density functional tight-binding (DFTB) method is combined with atomistic Green's function technique. The results show that curved GBs have lower thermal conductance than linear GBs. Its magnitude depends on the length of the curvature and out-of-plane structural distortions at the boundary, having stronger influence the latter one. Moreover, it is found that by increasing the defects at the boundary, the transport properties can strongly be reduced in comparison to the effect produced by heating up the boundary region. This is due to the large reduction of the phonon transmission for in-plane and out-of-plane vibrational modes after increasing the structural disorder in the GBs. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim},
      author_keywords={DFTB calculations; grain boundaries; graphene; Landauer theory; phonon transport},
      keywords={Grain boundaries; Graphene; Transport properties, Density functional tight binding method; Green's function technique; Landauer; Phonon transmissions; Phonon transport; Structural disorders; Structural distortions; Thermal conductance, Phonons},
      correspondence_address1={Sevinçli, H.; Department of Materials Science and Engineering, Turkey; email: haldunsevincli@iyte.edu.tr},
      publisher={Wiley-VCH Verlag},
      issn={21983844},
      language={English},
      abbrev_source_title={Adv. Sci.},
      document_type={Article},
      source={Scopus},
      }

  • Photosensitive Cationic Azobenzene Surfactants: Thermodynamics of Hydration and the Complex Formation with Poly(methacrylic acid)
    • M. Montagna, O. Guskova
    • Langmuir 34, 311-321 (2018)
    • DOI   Abstract  

      In this computational work, we investigate the photosensitive cationic surfactants with the trimethylammonium or polyamine hydrophilic head and the azobenzene-containing hydrophobic tail. The azobenzene-based molecules are known to undergo a reversible trans-cis-trans isomerization reaction when subjected to UV-visible light irradiation. Combining the density functional theory and the all-atom molecular dynamics simulations, the structural and the hydration properties of the trans- and the cis-isomers and their interaction with the oppositely charged poly(methacrylic acid) in aqueous solution are investigated. We establish and quantify the correlations of the molecular structure and the isomerization state of the surfactants and their hydrophilicity/hydrophobicity and the self-assembling altered by light. For this reason, we compare the hydration free energies of the trans- and the cis-isomers. Moreover, the investigations of the interaction strength between the azobenzene molecules and the polyanion provide additional elucidations of the recent experimental and theoretical studies on the light triggered reversible deformation behavior of the microgels and the polymer brushes loaded with azobenzene surfactants. © 2017 American Chemical Society.

      @ARTICLE{Montagna2018311,
      author={Montagna, M. and Guskova, O.},
      title={Photosensitive Cationic Azobenzene Surfactants: Thermodynamics of Hydration and the Complex Formation with Poly(methacrylic acid)},
      journal={Langmuir},
      year={2018},
      volume={34},
      number={1},
      pages={311-321},
      doi={10.1021/acs.langmuir.7b03638},
      note={cited By 34},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039037259&doi=10.1021%2facs.langmuir.7b03638&partnerID=40&md5=17c63f26a364a64b2afdeec64c452ae8},
      affiliation={Institute Theory of Polymers, Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Dresden, D-01069, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, D-01062, Germany},
      abstract={In this computational work, we investigate the photosensitive cationic surfactants with the trimethylammonium or polyamine hydrophilic head and the azobenzene-containing hydrophobic tail. The azobenzene-based molecules are known to undergo a reversible trans-cis-trans isomerization reaction when subjected to UV-visible light irradiation. Combining the density functional theory and the all-atom molecular dynamics simulations, the structural and the hydration properties of the trans- and the cis-isomers and their interaction with the oppositely charged poly(methacrylic acid) in aqueous solution are investigated. We establish and quantify the correlations of the molecular structure and the isomerization state of the surfactants and their hydrophilicity/hydrophobicity and the self-assembling altered by light. For this reason, we compare the hydration free energies of the trans- and the cis-isomers. Moreover, the investigations of the interaction strength between the azobenzene molecules and the polyanion provide additional elucidations of the recent experimental and theoretical studies on the light triggered reversible deformation behavior of the microgels and the polymer brushes loaded with azobenzene surfactants. © 2017 American Chemical Society.},
      keywords={Cationic surfactants; Computation theory; Density functional theory; Dyes; Hydration; Hydrophilicity; Isomerization; Isomers; Light; Light sensitive materials; Molecular dynamics; Molecules; Photosensitivity; Reaction kinetics; Solutions; Surface active agents; Thermodynamics, Azobenzene molecules; Azobenzene surfactant; Cis-trans Isomerization; Hydration free energies; Molecular dynamics simulations; Poly (methacrylic acid); Reversible deformation; Uv-visible light irradiations, Azobenzene},
      correspondence_address1={Montagna, M.; Institute Theory of Polymers, Hohe Str. 6, Germany; email: montagna@ipfdd.de},
      publisher={American Chemical Society},
      issn={07437463},
      coden={LANGD},
      pubmed_id={29228776},
      language={English},
      abbrev_source_title={Langmuir},
      document_type={Article},
      source={Scopus},
      }

  • Morphological evolution of Ge/Si nano-strips driven by Rayleigh-like instability
    • M. Salvalaglio, P. Zaumseil, Y. Yamamoto, O. Skibitzki, R. Bergamaschini, T. Schroeder, A. Voigt, G. Capellini
    • Applied Physics Letters 112, 022101 (2018)
    • DOI   Abstract  

      We present the morphological evolution obtained during the annealing of Ge strips grown on Si ridges as a prototypical process for 3D device architectures and nanophotonic applications. In particular, the morphological transition occurring from Ge/Si nanostrips to nanoislands is illustrated. The combined effect of performing annealing at different temperatures and varying the lateral size of the Si ridge underlying the Ge strips is addressed by means of a synergistic experimental and theoretical analysis. Indeed, three-dimensional phase-field simulations of surface diffusion, including the contributions of both surface and elastic energy, are exploited to understand the outcomes of annealing experiments. The breakup of Ge/Si strips, due to the activation of surface diffusion at high temperature, is found to be mainly driven by surface-energy reduction, thus pointing to a Rayleigh-like instability. The residual strain is found to play a minor role, only inducing local effects at the borders of the islands and an enhancement of the instability. © 2018 Author(s).

      @ARTICLE{Salvalaglio2018,
      author={Salvalaglio, M. and Zaumseil, P. and Yamamoto, Y. and Skibitzki, O. and Bergamaschini, R. and Schroeder, T. and Voigt, A. and Capellini, G.},
      title={Morphological evolution of Ge/Si nano-strips driven by Rayleigh-like instability},
      journal={Applied Physics Letters},
      year={2018},
      volume={112},
      number={2},
      doi={10.1063/1.5007937},
      art_number={022101},
      note={cited By 10},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040460434&doi=10.1063%2f1.5007937&partnerID=40&md5=b94142a49bee639a2491a29dd8366f39},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, 01062, Germany; IHP, Im Technologiepark 25, Frankfurt (Oder), 15236, Germany; Department of Materials Science, Università di Milano-Bicocca, Via R. Cozzi 55, Milano, I-20126, Italy; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01062, Germany; Department of Sciences, Università Roma Tre, Viale Marconi 446, Roma, I-00146, Italy},
      abstract={We present the morphological evolution obtained during the annealing of Ge strips grown on Si ridges as a prototypical process for 3D device architectures and nanophotonic applications. In particular, the morphological transition occurring from Ge/Si nanostrips to nanoislands is illustrated. The combined effect of performing annealing at different temperatures and varying the lateral size of the Si ridge underlying the Ge strips is addressed by means of a synergistic experimental and theoretical analysis. Indeed, three-dimensional phase-field simulations of surface diffusion, including the contributions of both surface and elastic energy, are exploited to understand the outcomes of annealing experiments. The breakup of Ge/Si strips, due to the activation of surface diffusion at high temperature, is found to be mainly driven by surface-energy reduction, thus pointing to a Rayleigh-like instability. The residual strain is found to play a minor role, only inducing local effects at the borders of the islands and an enhancement of the instability. © 2018 Author(s).},
      keywords={Annealing; Surface diffusion, Annealing experiments; Device architectures; Energy reduction; Morphological evolution; Morphological transitions; Phase-field simulation; Rayleigh-like instabilities; Residual strains, Germanium},
      publisher={American Institute of Physics Inc.},
      issn={00036951},
      coden={APPLA},
      language={English},
      abbrev_source_title={Appl Phys Lett},
      document_type={Article},
      source={Scopus},
      }

  • Erratum: The interplay of curvature and vortices in flow on curved surfaces
    • S. Reuther, A. Voigt
    • Multiscale Modeling and Simulation 16, 1448-1453 (2018)
    • DOI   Abstract  

      We here correct the model and the derivation of the vorticity-stream function formulation for the incompressible surface Navier-Stokes equation on moving surfaces, proposed in [S. Reuther and A. Voigt, Multiscale Model. Simul., 13 (2015), pp. 632-643]. © 2018 Society for Industrial and Applied Mathematics.

      @ARTICLE{Reuther20181448,
      author={Reuther, S. and Voigt, A.},
      title={Erratum: The interplay of curvature and vortices in flow on curved surfaces},
      journal={Multiscale Modeling and Simulation},
      year={2018},
      volume={16},
      number={3},
      pages={1448-1453},
      doi={10.1137/18M1176464},
      note={cited By 3},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054254018&doi=10.1137%2f18M1176464&partnerID=40&md5=ee235164db559dec332be0a8f10dc1d5},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, Germany; Institute of Scientific Computing, Technische Universität Dresden, Dresden Center for Computational Materials Science (DCMS), Center for Systems Biology Dresden (CSBD), Dresden, Germany},
      abstract={We here correct the model and the derivation of the vorticity-stream function formulation for the incompressible surface Navier-Stokes equation on moving surfaces, proposed in [S. Reuther and A. Voigt, Multiscale Model. Simul., 13 (2015), pp. 632-643]. © 2018 Society for Industrial and Applied Mathematics.},
      author_keywords={Curved surfaces; Geometric force; Interface},
      keywords={Incompressible flow; Interfaces (materials), Curved surfaces; Geometric force; Moving surfaces; Multi-scale Modeling; Vorticity stream function formulation, Navier Stokes equations},
      publisher={Society for Industrial and Applied Mathematics Publications},
      issn={15403459},
      language={English},
      abbrev_source_title={Multiscale Model. Simul.},
      document_type={Article},
      source={Scopus},
      }

  • Copper electroplating with polyethylene glycol: Part II. Experimental analysis and determination of model parameters
    • H. Yang, R. Krause, C. Scheunert, R. Liske, B. Uhlig, A. Preusse, A. Dianat, M. Bobeth, G. Cuniberti
    • Journal of the Electrochemical Society 165, D13-D22 (2018)
    • DOI   Abstract  

      In the electrochemical deposition of copper on structured substrates, additives are commonly used as ingredients to refine the copper thin film properties. By means of cyclovoltametric (CV) measurements, we examine the process behavior of the additives PEG (polyethylene glycol) and chloride ions over a wide range of experimental parameters relevant for production-like conditions. In this plating process, additives practically are neither consumed in chemical reactions nor are they incorporated into the growing copper film. To understand the observed complex hysteresis behavior of the deposition current in CV scans, we have recently proposed a model which is able to qualitatively explain this behavior without supposing additive consumption. In the present study, we fit crucial parameters of this model from the experimental data to increase its predictive power. The quantitative agreement of performed simulations of CV scans with the measured scans demonstrates the validity of the proposed copper deposition model. Equipped with the determined parameter set, the model can help to optimize the copper plating process in industrial applications. © 2018 The Electrochemical Society.

      @ARTICLE{Yang2018D13,
      author={Yang, H. and Krause, R. and Scheunert, C. and Liske, R. and Uhlig, B. and Preusse, A. and Dianat, A. and Bobeth, M. and Cuniberti, G.},
      title={Copper electroplating with polyethylene glycol: Part II. Experimental analysis and determination of model parameters},
      journal={Journal of the Electrochemical Society},
      year={2018},
      volume={165},
      number={2},
      pages={D13-D22},
      doi={10.1149/2.0081802jes},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048421876&doi=10.1149%2f2.0081802jes&partnerID=40&md5=09acb202cb1cf1a2df474739b07807ed},
      affiliation={Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden, 01069, Germany; Fraunhofer Institute for Photonic Microsystems IPMS, Center Nanoelectronic Technologies, Dresden, 01099, Germany; Globalfoundries Dresden Module One LLC and Co. KG, Dresden, 01109, Germany; Dresden Center for Computational Materials Science (DCCMS), TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden (CfAED), Dresden, 01187, Germany},
      abstract={In the electrochemical deposition of copper on structured substrates, additives are commonly used as ingredients to refine the copper thin film properties. By means of cyclovoltametric (CV) measurements, we examine the process behavior of the additives PEG (polyethylene glycol) and chloride ions over a wide range of experimental parameters relevant for production-like conditions. In this plating process, additives practically are neither consumed in chemical reactions nor are they incorporated into the growing copper film. To understand the observed complex hysteresis behavior of the deposition current in CV scans, we have recently proposed a model which is able to qualitatively explain this behavior without supposing additive consumption. In the present study, we fit crucial parameters of this model from the experimental data to increase its predictive power. The quantitative agreement of performed simulations of CV scans with the measured scans demonstrates the validity of the proposed copper deposition model. Equipped with the determined parameter set, the model can help to optimize the copper plating process in industrial applications. © 2018 The Electrochemical Society.},
      keywords={Additives; Chlorine compounds; Polyethylene glycols; Polyethylenes; Reduction, Copper electroplating; Crucial parameters; Deposition current; Determination of model parameters; Experimental analysis; Experimental parameters; Quantitative agreement; Structured substrate, Electrochemical deposition},
      publisher={Electrochemical Society Inc.},
      issn={00134651},
      coden={JESOA},
      language={English},
      abbrev_source_title={J Electrochem Soc},
      document_type={Article},
      source={Scopus},
      }

  • Solving the incompressible surface Navier-Stokes equation by surface finite elements
    • S. Reuther, A. Voigt
    • Physics of Fluids 30, 012107 (2018)
    • DOI   Abstract  

      We consider a numerical approach for the incompressible surface Navier-Stokes equation on surfaces with arbitrary genus g(S). The approach is based on a reformulation of the equation in Cartesian coordinates of the embedding R3, penalization of the normal component, a Chorin projection method, and discretization in space by surface finite elements for each component. The approach thus requires only standard ingredients which most finite element implementations can offer. We compare computational results with discrete exterior calculus simulations on a torus and demonstrate the interplay of the flow field with the topology by showing realizations of the Poincaré-Hopf theorem on n-tori. © 2018 Author(s).

      @ARTICLE{Reuther2018,
      author={Reuther, S. and Voigt, A.},
      title={Solving the incompressible surface Navier-Stokes equation by surface finite elements},
      journal={Physics of Fluids},
      year={2018},
      volume={30},
      number={1},
      doi={10.1063/1.5005142},
      art_number={012107},
      note={cited By 47},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040778742&doi=10.1063%2f1.5005142&partnerID=40&md5=873d51ed9bd562655f60de7e4f52206a},
      affiliation={Institute of Scientific Computing, Technische Universität Dresden, Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), Dresden, Germany; Center for Systems Biology Dresden (CSBD), Dresden, Germany},
      abstract={We consider a numerical approach for the incompressible surface Navier-Stokes equation on surfaces with arbitrary genus g(S). The approach is based on a reformulation of the equation in Cartesian coordinates of the embedding R3, penalization of the normal component, a Chorin projection method, and discretization in space by surface finite elements for each component. The approach thus requires only standard ingredients which most finite element implementations can offer. We compare computational results with discrete exterior calculus simulations on a torus and demonstrate the interplay of the flow field with the topology by showing realizations of the Poincaré-Hopf theorem on n-tori. © 2018 Author(s).},
      keywords={Calculations; Computation theory; Finite element method; Topology; Viscous flow, Cartesian coordinate; Computational results; Discrete exterior calculus; Finite element implementation; Normal component; Numerical approaches; Projection method; Surface finite elements, Navier Stokes equations},
      publisher={American Institute of Physics Inc.},
      issn={10706631},
      coden={PHFLE},
      language={English},
      abbrev_source_title={Phys. Fluids},
      document_type={Article},
      source={Scopus},
      }

  • Microscale finite element model of brittle multifilament yarn failure behavior
    • O. Döbrich, T. Gereke, M. Hengstermann, C. Cherif
    • Journal of Industrial Textiles 47, 870-882 (2018)
    • DOI   Abstract  

      A microscale model of multifilament reinforcement yarns made of technical carbon fibers is established based on the finite element method. The model is used to perform simulations of tensile failure. The failure behavior of dry multifilament carbon yarns is modeled using a maximum stress criterion with statistical distribution of the strength. The maximum stress is assigned to every single element and varied according to a normal distribution found in experimental tests of single filaments. The Weibull distribution is used for calculating the local failure stress. The material parameters are calculated in function of the element size to account for the volume-specific statistical breaking effect. Representative simulations of the tensile failure behavior prove the concept of the introduced assumptions. © 2016, © The Author(s) 2016.

      @ARTICLE{Döbrich2018870,
      author={Döbrich, O. and Gereke, T. and Hengstermann, M. and Cherif, C.},
      title={Microscale finite element model of brittle multifilament yarn failure behavior},
      journal={Journal of Industrial Textiles},
      year={2018},
      volume={47},
      number={5},
      pages={870-882},
      doi={10.1177/1528083716674908},
      note={cited By 4},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038589632&doi=10.1177%2f1528083716674908&partnerID=40&md5=77a25924f793f8cb9d5bbc8c31cc7a50},
      affiliation={Institute of Textile Machinery and High Performance Material Technology, Faculty of Mechanical Science and Engineering, Technische Universität Dresden, Dresden, Germany; Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden, Germany},
      abstract={A microscale model of multifilament reinforcement yarns made of technical carbon fibers is established based on the finite element method. The model is used to perform simulations of tensile failure. The failure behavior of dry multifilament carbon yarns is modeled using a maximum stress criterion with statistical distribution of the strength. The maximum stress is assigned to every single element and varied according to a normal distribution found in experimental tests of single filaments. The Weibull distribution is used for calculating the local failure stress. The material parameters are calculated in function of the element size to account for the volume-specific statistical breaking effect. Representative simulations of the tensile failure behavior prove the concept of the introduced assumptions. © 2016, © The Author(s) 2016.},
      author_keywords={carbon fiber; failure; FEM; strength; Weibull; yarn},
      keywords={Carbon fibers; Computer system recovery; Normal distribution; Weibull distribution; Wool; Yarn, Experimental test; Material parameter; Maximum stress criterions; Micro scale models; Multifilament yarns; Statistical distribution; strength; Weibull, Finite element method, Failure; Finite Element Analysis; Statistical Distribution; Yarn},
      correspondence_address1={Döbrich, O.; Institute of Textile Machinery and High Performance Material Technology, Germany; email: oliver.doebrich@tu-dresden.de},
      publisher={SAGE Publications Ltd},
      issn={15280837},
      coden={JINTF},
      language={English},
      abbrev_source_title={J. Ind. Text.},
      document_type={Article},
      source={Scopus},
      }

  • Feasible Device Architectures for Ultrascaled CNTFETs
    • A. Pacheco-Sanchez, F. Fuchs, S. Mothes, A. Zienert, J. Schuster, S. Gemming, M. Claus
    • IEEE Transactions on Nanotechnology 17, 100-107 , 8113541 (2018)
    • DOI   Abstract  

      Feasible device architectures for ultrascaled carbon nanotubes field-effect transistors (CNTFETs) are studied down to 5.9 nm using a multiscale simulation approach covering electronic quantum transport simulations and numerical device simulations. Schottky-like and ohmiclike contacts are considered. The simplified approach employed in the numerical device simulator is critically evaluated and verified by means of comparing the results with electronic quantum simulation results of an identical device. Different performance indicators, such as the switching speed, switching energy, the subthreshold slope, Ion/Ioff-ratio, among others, are extracted for different device architectures. These values guide the evaluation of the technology for different application scenarios. For high-performance logic applications, the buried gate CNTFET is claimed to be the most suitable structure. © 2017 IEEE.

      @ARTICLE{Pacheco-Sanchez2018100,
      author={Pacheco-Sanchez, A. and Fuchs, F. and Mothes, S. and Zienert, A. and Schuster, J. and Gemming, S. and Claus, M.},
      title={Feasible Device Architectures for Ultrascaled CNTFETs},
      journal={IEEE Transactions on Nanotechnology},
      year={2018},
      volume={17},
      number={1},
      pages={100-107},
      doi={10.1109/TNANO.2017.2774605},
      art_number={8113541},
      note={cited By 13},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85035120535&doi=10.1109%2fTNANO.2017.2774605&partnerID=40&md5=d9e4fec18ddd6bcbb1b130a7adcf99bd},
      affiliation={Electron Devices and Integrated Circuits, Technische Universitat Dresden, Dresden, 01069, Germany; Center for Advancing Electronics Dresden, Technische Universitat Dresden, Dresden, 01069, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Dresden, 01328, Germany; Fraunhofer Institute for Electronic Nano Systems, Chemnitz, 09126, Germany; Microtechnologies Chemnitz, University of Technology, Chemnitz, 09111, Germany; Dresden Center for Computational Materials Science, Technische Universitat Dresden, Dresden, 01069, Germany; Institute of Physics, Chemnitz University of Technology, Chemnitz, 09111, Germany},
      abstract={Feasible device architectures for ultrascaled carbon nanotubes field-effect transistors (CNTFETs) are studied down to 5.9 nm using a multiscale simulation approach covering electronic quantum transport simulations and numerical device simulations. Schottky-like and ohmiclike contacts are considered. The simplified approach employed in the numerical device simulator is critically evaluated and verified by means of comparing the results with electronic quantum simulation results of an identical device. Different performance indicators, such as the switching speed, switching energy, the subthreshold slope, Ion/Ioff-ratio, among others, are extracted for different device architectures. These values guide the evaluation of the technology for different application scenarios. For high-performance logic applications, the buried gate CNTFET is claimed to be the most suitable structure. © 2017 IEEE.},
      author_keywords={Atomistic simulation; Channel scaling; CNTFET; Electronic quantum simulation; Ion/Ioff-ratio; Multiscale modeling; Numerical device simulation; Subthreshold slope; Switching characteristics},
      keywords={Architecture; Electronic design automation; Quantum electronics, Atomistic simulations; channel scaling; CNTFET; Electronic quantum; Multi-scale Modeling; Subthreshold slope; Switching characteristics; TCAD, Quantum chemistry},
      correspondence_address1={Pacheco-Sanchez, A.; Electron Devices and Integrated Circuits, Germany; email: anibal.pacheco-sanchez@mailbox.tu-dresden.de},
      publisher={Institute of Electrical and Electronics Engineers Inc.},
      issn={1536125X},
      language={English},
      abbrev_source_title={IEEE Trans. Nanotechnol.},
      document_type={Article},
      source={Scopus},
      }

2017

  • Molecular and Ionic Dipole Effects on the Electronic Properties of Si-/SiO2-Grafted Alkylamine Monolayers
    • A. Gankin, R. Sfez, E. Mervinetsky, J. Buchwald, A. Dianat, L. Medrano Sandonas, R. Gutierrez, G. Cuniberti, S. Yitzchaik
    • ACS Applied Materials and Interfaces 9, 44873-44879 (2017)
    • DOI   Abstract  

      In this work, we demonstrate the tunability of electronic properties of Si/SiO2 substrates by molecular and ionic surface modifications. The changes in the electronic properties such as the work function (WF) and electron affinity were experimentally measured by the contact potential difference technique and theoretically supported by density functional theory calculations. We attribute these molecular electronic effects mainly to the variations of molecular and surface dipoles of the ionic and neutral species. We have previously shown that for the alkylhalide monolayers, changing the tail group from Cl to I decreased the WF of the substrate. Here, we report on the opposite trend of WF changes, that is, the increase of the WF, obtained by using the anions of these halides from Cl- to I-. This trend was observed on self-assembled alkylammonium halide (-NH3+ X-, where X- = Cl-, Br-, or I-) monolayer-modified substrates. The monolayer’s formation was supported by ellipsometry measurements, X-ray photoelectron spectroscopy, and atomic force microscopy. Comparison of the theoretical and experimental data suggests that the ionic surface dipole depends mainly on the polarizability and the position of the counter halide anion along with the organization and packaging of the layer. The described ionic modification can be easily used for facile tailoring and design of the electronic properties Si/SiO2 substrates for various device applications. © 2017 American Chemical Society.

      @ARTICLE{Gankin201744873,
      author={Gankin, A. and Sfez, R. and Mervinetsky, E. and Buchwald, J. and Dianat, A. and Medrano Sandonas, L. and Gutierrez, R. and Cuniberti, G. and Yitzchaik, S.},
      title={Molecular and Ionic Dipole Effects on the Electronic Properties of Si-/SiO2-Grafted Alkylamine Monolayers},
      journal={ACS Applied Materials and Interfaces},
      year={2017},
      volume={9},
      number={51},
      pages={44873-44879},
      doi={10.1021/acsami.7b12218},
      note={cited By 9},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040042319&doi=10.1021%2facsami.7b12218&partnerID=40&md5=a6ca11cd98c94f1ca445a68f4b5f66d8},
      affiliation={Institute of Chemistry, Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem, 91904, Israel; Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, 91904, Israel; Department of Advanced Materials Engineering, Azrieli College of Engineering, Jerusalem, 9103501, Israel; Institute for Materials Science, Max Bergmann Center of Biomaterials, TU Dresden, Dresden, 01062, Germany; Dresden Center for Computational Materials Science, TU Dresden, Dresden, 01062, Germany; Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01062, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, 01187, Germany},
      abstract={In this work, we demonstrate the tunability of electronic properties of Si/SiO2 substrates by molecular and ionic surface modifications. The changes in the electronic properties such as the work function (WF) and electron affinity were experimentally measured by the contact potential difference technique and theoretically supported by density functional theory calculations. We attribute these molecular electronic effects mainly to the variations of molecular and surface dipoles of the ionic and neutral species. We have previously shown that for the alkylhalide monolayers, changing the tail group from Cl to I decreased the WF of the substrate. Here, we report on the opposite trend of WF changes, that is, the increase of the WF, obtained by using the anions of these halides from Cl- to I-. This trend was observed on self-assembled alkylammonium halide (-NH3+ X-, where X- = Cl-, Br-, or I-) monolayer-modified substrates. The monolayer's formation was supported by ellipsometry measurements, X-ray photoelectron spectroscopy, and atomic force microscopy. Comparison of the theoretical and experimental data suggests that the ionic surface dipole depends mainly on the polarizability and the position of the counter halide anion along with the organization and packaging of the layer. The described ionic modification can be easily used for facile tailoring and design of the electronic properties Si/SiO2 substrates for various device applications. © 2017 American Chemical Society.},
      author_keywords={contact potential difference; DFT; ionic dipole; molecular dipole; self-assembled monolayer; work function},
      keywords={Atomic force microscopy; Chip scale packages; Density functional theory; Design for testability; Electron affinity; Electronic properties; Monolayers; Negative ions; Self assembled monolayers; Silicon; Work function; X ray photoelectron spectroscopy, Contact potential difference; Device application; Ellipsometry measurements; ionic dipole; Ionic modification; Molecular dipole; Molecular-electronic effects; Polarizabilities, Substrates},
      correspondence_address1={Gutierrez, R.; Institute for Materials Science, Germany; email: rafael.gutierrez@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19448244},
      pubmed_id={29206026},
      language={English},
      abbrev_source_title={ACS Appl. Mater. Interfaces},
      document_type={Article},
      source={Scopus},
      }

  • On-Surface Annulation Reaction Cascade for the Selective Synthesis of Diindenopyrene
    • F. Eisenhut, T. Lehmann, A. Viertel, D. Skidin, J. Krüger, S. Nikipar, D. A. Ryndyk, C. Joachim, S. Hecht, F. Moresco, G. Cuniberti
    • ACS Nano 11, 12419-12425 (2017)
    • DOI   Abstract  

      We investigated the thermally induced on-surface cyclization of 4,10-bis(2′-bromo-4′-methylphenyl)-1,3-dimethylpyrene to form the previously unknown, nonalternant polyaromatic hydrocarbon diindeno[1,2,3-cd:1′,2′,3′-mn]pyrene on Au(111) using scanning tunneling microscopy and spectroscopy. The observed unimolecular reaction involves thermally induced debromination followed by selective ring closure to fuse the neighboring benzene moieties via a five-membered ring. The structure of the product has been verified experimentally as well as theoretically. Our results demonstrate that on-surface reactions give rise to unusual chemical reactivities and selectivities and provide access to nonalternant polyaromatic molecules. © 2017 American Chemical Society.

      @ARTICLE{Eisenhut201712419,
      author={Eisenhut, F. and Lehmann, T. and Viertel, A. and Skidin, D. and Krüger, J. and Nikipar, S. and Ryndyk, D.A. and Joachim, C. and Hecht, S. and Moresco, F. and Cuniberti, G.},
      title={On-Surface Annulation Reaction Cascade for the Selective Synthesis of Diindenopyrene},
      journal={ACS Nano},
      year={2017},
      volume={11},
      number={12},
      pages={12419-12425},
      doi={10.1021/acsnano.7b06459},
      note={cited By 16},
      url={https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040080951&doi=10.1021%2facsnano.7b06459&partnerID=40&md5=afac22918a65c6ac7af75dcdf3c490ec},
      affiliation={Institute for Materials Science, Max Bergmann Center of Biomaterials, Center for Advancing Electronics Dresden, TU Dresden, Dresden, 01069, Germany; Department of Chemistry and IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, Berlin, 12489, Germany; Bremen Center for Computational Materials Science, Universität Bremen, Bremen, 28359, Germany; GNS and MANA Satellite, CEMES, CNRS, 29 rue J. Marvig, Cedex Toulouse, 31055, France; Dresden Center for Computational Materials Science (DCMS), TU Dresden, Dresden, 01069, Germany},
      abstract={We investigated the thermally induced on-surface cyclization of 4,10-bis(2′-bromo-4′-methylphenyl)-1,3-dimethylpyrene to form the previously unknown, nonalternant polyaromatic hydrocarbon diindeno[1,2,3-cd:1′,2′,3′-mn]pyrene on Au(111) using scanning tunneling microscopy and spectroscopy. The observed unimolecular reaction involves thermally induced debromination followed by selective ring closure to fuse the neighboring benzene moieties via a five-membered ring. The structure of the product has been verified experimentally as well as theoretically. Our results demonstrate that on-surface reactions give rise to unusual chemical reactivities and selectivities and provide access to nonalternant polyaromatic molecules. © 2017 American Chemical Society.},
      author_keywords={density functional theory; nonalternant polyaromatic hydrocarbons; on-surface reaction; reaction mechanism; scanning tunneling microscopy; single-molecule chemistry},
      keywords={Density functional theory; Hydrocarbons; Molecules; Scanning tunneling microscopy, Annulation reactions; Five-membered rings; Polyaromatic hydrocarbons; Polyaromatic molecules; Reaction mechanism; Scanning tunneling microscopy and spectroscopy; Single-molecule chemistry; Unimolecular reactions, Surface reactions},
      correspondence_address1={Moresco, F.; Institute for Materials Science, Germany; email: francesca.moresco@tu-dresden.de},
      publisher={American Chemical Society},
      issn={19360851},
      pubmed_id={29136462},
      language={English},
      abbrev_source_title={ACS Nano},
      document_type={Article},
      source={Scopus},
      }

  • Modeling and Simulation of Electrochemical Cells under Applied Voltage
    • M. Rossi, T. Wallmersperger, S. Neukamm, K. Padberg-Gehle
    • Electrochimica Acta 258, 241-254 (2017)
    • DOI   Abstract  

      The behavior of an electrochemical thin film under input voltage (potentiostatic) conditions is numerically investigated. Thin films are used in micro-batteries and proton-exchange-membrane fuel cells: these devices are expected to play a significant role in the next generation energy systems for use in vehicles as a replacement to combustion engines. The electrochemical investigation of thin films is a relevant topic for a wide range of applications such as hydrogels, ionic polymer metal composites, biological membranes, and treatment of tumors. In this work, a continuum-based model is presented in order to describe the behavior of thin membranes. The electrochemical behavior of thin membranes is usually hard to investigate with experiments. Therefore, numerical simulations are carried out in order to enable a better understanding of the chemical reactions occurring within microscopic regions at the electrode/electrolyte interfaces. Diffusive-migrative ionic fluxes and electric field distribution are considered. A one-dimensional domain is employed. The fully-coupled electrochemical field is given by the Poisson-Nernst-Planck equations. The model involves initial and interface/boundary conditions appropriate for an electrolytic/galvanic cell. The latter are the Stern layer conditions for polarization (or diffuse charge) effects and the Frumkin-Butler-Volmer equations for electrochemical kinetics of chemical reactions. Time-dependent numerical simulations within a fi