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

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 LiCoO2. Program summary: Program Title: FourPhonon CPC Library link to program files: https://doi.org/10.17632/jjcwt5436h.1 Developer's repository link: https://github.com/FourPhonon Licensing provisions: GNU General Public License version 3 Programming language: Fortran 90, MPI Nature of problem: Calculation of lattice thermal conductivity and related quantities, determination of both three-phonon and four-phonon scattering rates Solution method: Four-phonon scattering rates at RTA level, adaptive broadening scheme Additional comments including restrictions and unusual features: For a productive run, one needs to use High Performance Computing facilities and it takes several hours to several days to finish calculations