Ab Initio Phonon Dispersions for PbTe

TL;DR

This paper presents first-principles calculations of PbTe phonon dispersions, revealing near instabilities at the zone center and strong volume dependence, which relate to its thermal conductivity properties.

Contribution

It provides new ab initio insights into phonon behavior in PbTe, including effects of compression on phonon stability and dispersion.

Findings

Near instability of optic branch at zone center at experimental lattice parameter

Rapid hardening of phonon modes with compression

Strong volume dependence affecting thermal conductivity

Abstract

We report first principles calculations of the phonon dispersions of PbTe both for its observed structure and under compression. At the experimental lattice parameter we find a near instability of the optic branch at the zone center, in accord with experimental observations.This hardens quickly towards the zone boundary. There is also a very strong volume dependence of this mode, which is rapidly driven away from an instability by compression. These results are discussed inrelation to the thermal conductivity of the material.