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O: Fachverband Oberflächenphysik
O 2: Heterostructures, interfaces and surfaces (joint session HL/O)
O 2.3: Vortrag
Montag, 16. März 2020, 10:00–10:15, POT 151
direct insight into the structure-property relation of interfaces from first-principles crystal structure prediction — •lin sun1, miguel a. l. marques2,3, and silvana botti1,3 — 1Institut für Festkörpertheorie und Optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany — 2Institut für Physik - Martin-Luther-Universität Halle, D-06099 Halle, Germany — 3European Theoretical Spectroscopy Facility
In this work we develop an efficient and accurate computational scheme aimed at a full understanding of heterogeneous materials. Our approach is a variant of the minima-hopping method for global crystal structure prediction. Specifically, we implement a constraint library and we enable variations of the atomic density in proximity to the interface. DFT and DFTB calculations supply necessary energy and forces to the minima-hopping algorithm. With this method, we find a rich polymorphism in the reconstructions of tilt boundaries in polycrystalline silicon, with recurring bonding patterns that we classify in increasing energetic order. In several cases, we succeed in identifying atomic arrangements that are significantly more stable than previously predicted structures, while in other cases we show that the algorithm can recover, without experimental input, geometries that had been built by hand to match experimental data. We extend then the calculations to other group IV elements, and compare lowest energy reconstructions of C, Si, Ge and Sn grain boundaries. Finally, a clear relation between bonding patterns and electrically active interface states is unveiled and discussed.