Thermal Conductivity of MgO Periclase from Equilibrium First Principles Molecular Dynamics

Abstract

A method is presented by which the lattice thermal conductivity can be computed from first principles using relatively small system sizes and simulation times. The method uses the relation for thermal conductivity of a kinetic gas, with phonon lifetimes and frequencies determined by combining equilibrium first principles molecular dynamics and first principles lattice dynamics. To illustrate the method, the lattice conductivity is computed for MgO periclase. For individual wave vectors and vibrational modes, phonon lifetimes in periclase are found to be inversely proportional to temperature, with optic modes shorter lived than acoustic modes, contributing only approximately 5% to the lattice conductivity. Computed thermal conductivity values show excellent agreement with experimental measurements, and suggest that the radiative contribution to thermal transport in periclase starts playing a role above approximately 1500 K.