Origin of anomalous anharmonic lattice dynamics of lead telluride

TL;DR

This paper investigates the unusual anharmonic lattice dynamics of lead telluride using first-principles molecular dynamics, revealing that large nearest-neighbor cubic interatomic force constants cause local distortions and specific phonon features.

Contribution

It identifies the origin of anomalous anharmonic behavior in lead telluride as due to large nearest-neighbor cubic IFCs, supported by first-principles simulations.

Findings

Reproduces peak asymmetry in radial distribution functions.

Explains double peaks in transverse optical phonons.

Links local distortions to large cubic IFCs.

Abstract

The origin of the anomalous anharmonic lattice dynamics of lead telluride is investigated using molecular dynamics simulations with interatomic force constants (IFCs) up to quartic terms obtained from first principles. The calculations reproduce the peak asymmetry of the radial distribution functions and the double peaks of transverse optical phonon previously observed with neutron diffraction and scattering experiments. They are identified to be due to the extremely large nearest-neighbor cubic IFCs in the [100] direction. The outstanding strength of the nearest-neighbor cubic IFCs relative to the longer-range ones explains the reason why the distortion in the radial distribution function is local.