ALATDYN: a set of Anharmonic LATtice DYNamics codes to compute thermodynamic and thermal transport properties of crystalline solids

TL;DR

ALATDYN is a comprehensive lattice dynamics software that calculates thermodynamic, elastic, and thermal transport properties of crystalline solids from force and energy data, integrating DFT and molecular dynamics inputs.

Contribution

It introduces a versatile tool that combines anharmonic lattice dynamics, Boltzmann transport, and molecular dynamics to analyze crystalline materials' properties from various data sources.

Findings

Applied to germanium crystal for validation

Calculates elastic, thermodynamic, and thermal transport properties

Enables MD simulations for anharmonic and defect effects

Abstract

We introduce a lattice dynamics package which calculates elastic, thermodynamic and thermal transport properties of crystalline materials from data on their force and potential energy as a function of atomic positions. The data can come from density functional theory (DFT) calculations or classical molecular dynamics runs performed in a supercell. First, the model potential parameters, which are anharmonic force constants are extracted from the latter runs. Then, once the anharmonic model is defined, thermal conductivity and equilibrium properties at finite temperatures can be computed using lattice dynamics, Boltzmann transport theories, and a variational principle respectively. In addition, the software calculates the mechanical properties such as elastic tensor, Gruneisen parameters and the thermal expansion coefficient within the quasi-harmonic approximation (QHA). Phonons, elastic constants and thermodynamic properties results applied to the germanium crystal will be illustrated. Using the force constants as a force field, one may also perform molecular dynamics (MD) simulations in order to investigate the combined effects of anharmonicity and defect scattering beyond perturbation theory.