FourPhonon: An extension module to ShengBTE for computing four-phonon scattering rates and thermal conductivity

TL;DR

FourPhonon is an extension module integrated with ShengBTE that enables the calculation of four-phonon scattering rates and thermal conductivity in crystals, enhancing the accuracy of thermal transport modeling.

Contribution

It introduces a new computational module for four-phonon scattering within ShengBTE, including an adaptive energy broadening scheme and tools for calculating fourth-order interatomic force constants.

Findings

Successfully applied to Si, BAs, and LiCoO2

Preserves ShengBTE's features like parallelism and workflow

Provides improved thermal conductivity calculations

Abstract

FourPhonon is a computational package that can calculate four-phonon scattering rates in crystals. It is built within ShengBTE framework, which is a well-recognized lattice thermal conductivity solver based on Boltzmann transport equation. An adaptive energy broadening scheme is implemented for the calculation of four-phonon scattering rates. In analogy with $thirdorder.py$ in ShengBTE, we also provide a separate python script, $Fourthorder.py$, to calculate fourth-order interatomic force-constants. The extension module preserves all the nice features of the well-recognized lattice thermal conductivity solver ShengBTE, including good parallelism and straightforward workflow. In this paper, we discuss the general theory, program design, and example calculations on Si, BAs and $\mathrm{LiCoO_2}$.