A New Approach to Phonon Anharmonicity

TL;DR

This paper introduces an ab initio method to accurately compute anharmonic phonon peaks in dispersion curves using Hellmann-Feynman forces from supercell calculations, effectively capturing anharmonic effects at finite temperatures.

Contribution

It presents a novel approach combining ab initio calculations and atomic displacements to model phonon anharmonicity in materials.

Findings

Successfully applied to cubic PbTe and MgSiO3 crystals.

Accurately reproduces positions and shapes of anharmonic peaks.

Provides a practical tool for studying thermal properties of materials.

Abstract

An approach to compute the anharmonic peaks of the phonon dispersion curves through the ab initio calculated Hellmann-Feynman forces from a series of supercells with realistic atomic displacements of all atoms, which correspond to a given temperature, is reported. Obtained phonon dispersion bands are able to represent the positions and shapes of the anharmonic peaks. As example, the approach to cubic PbTe and perovskite MgSiO3 crystals is applied.