Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 47: Focused Session: Frontiers of Electronic Structure Theory 5 (jointly with HL and O)

TT 47.6: Vortrag

Mittwoch, 13. März 2013, 17:30–17:45, H36

Potential energy surface of BaTiO₃ explored with density-functional theory and classical force fields — •Joseph Fallon¹, David McComb², Arash Mostofi¹, and Paul Tangney¹ — ¹Imperial College London, London, UK — ²The Ohio State University, Columbus, USA

Much is known about the electronic structure of BaTiO₃, its phonon dispersions, and the energetics of its long wavelength lattice distortions. However, there is much more to learn about the potential energy surface (PES) on which the atoms move. We study the PES using a combination of density functional-theory (DFT) and a polarisable ionic model of interatomic bonding. Our force field is in close agreement with DFT on structures, the PES, and phonon frequencies and allows accurate large scale atomistic simulations of domain structures and dynamics to be performed. A key advantage of an atomistic model over the coarse grained models that are often used to simulate domain dynamics is that it allows the simulation of heterogeneous materials (e.g. grain boundaries, point defects). However, we also point out some features of the PES, which may be important to domain dynamics, that effective Hamiltonians based on the transverse optic soft mode eigenvector and the local strain fail to capture.