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MM: Fachverband Metall- und Materialphysik

MM 12: Poster session I

MM 12.17: Poster

Montag, 1. April 2019, 19:15–20:45, Poster C

A first-principle self-consistent phonon approach for studying the vibrational properties of the high-temperature phases of pervoskites. — •Sohaib Ehsan, Marco Arrigoni, Georg Madsen, and Peter Blaha — Institute of Materials Chemistry, Vienna University of Technology, Vienna, Austria

In this study we investigate the phonon properties of perovskites in their high-temperature phases by first- principle methods. We use BaTiO3 , which shows a stable cubic phase above 120 C, as a model material. Due to the presence of unstable phonon modes in the harmonic approximation, we include an-harmonicity by calculating self-consistently temperature-dependent interatomic force constants. We show that in this way we are able to reproduce the experimentally observed phonon dispersion relations. Such approach allows to predict other vibrational properties of these compounds, such as the transition temperature between the low- and high-symmetry phases and the lattice thermal conductivity.