Speaker
Description
Phonon dispersion relations characterize collective lattice vibrations in crystalline solids and provide fundamental insight into their vibrational properties. Within the harmonic approximation, which represents the quadratic expansion of the lattice potential energy around equilibrium, phonon dispersions can be obtained and are widely used to analyze basic lattice dynamical properties.
Nevertheless, the harmonic approximation does not incorporate phonon–phonon interactions and therefore cannot describe phonon scattering processes that are relevant to thermal transport phenomena such as lattice thermal conductivity. In addition, in temperature regimes where anharmonic effects become non-negligible, the resulting renormalization of phonon frequencies may require extensions beyond the harmonic framework.
In this work, we employ higher-order force constants to capture anharmonic phonon effects beyond the harmonic approximation. We investigate temperature-dependent phonon dispersions and analyze lattice thermal conductivity from first principles.
