Phonon anharmonicity and structural transitions – neutron scattering and first-principles simulations

Using a combination of inelastic neutron/x-ray scattering and first-principles simulations, we investigate anharmonic effects on phonons across phase transitions. This presentation will focus on transitions potentially associated with soft mode condensation. In particular, we will highlight results on phonons in SnS and SnSe across the high-temperature Pnma-Cmcm transition, in VO2 across the rutile-M1 transition, and NbNiTe2 across its subtle structural orthorhombic-monoclinic transition at 373K. The effects of phonon anharmonicity on thermal transport and thermodynamics will be discussed.