Lattice dynamics of anharmonic solids from first principles

TL;DR

This paper introduces a first-principles molecular dynamics-based method to accurately analyze lattice dynamics in solids, especially effective for strongly anharmonic systems where traditional methods fail.

Contribution

It presents a new extendable approach to extract harmonic and higher-order potential energy surfaces at finite temperatures from first-principles simulations.

Findings

Accurate phonon dispersion relations for bcc Li and Zr at finite temperature.

Method works well for strongly anharmonic systems.

Convergence and accuracy are straightforward to control.

Abstract

An accurate and easily extendable method to deal with lattice dynamics of solids is offered. It is based on first-principles molecular dynamics simulations and provides a consistent way to extract the best possible harmonic - or higher order - potential energy surface at finite temperatures. It is designed to work even for strongly anharmonic systems where the traditional quasiharmonic approximation fails. The accuracy and convergence of the method are controlled in a straightforward way. Excellent agreement of the calculated phonon dispersion relations at finite temperature with experimental results for bcc Li and bcc Zr is demonstrated.