Thermal Conductivity of MgO at High Pressures

TL;DR

This paper presents the first non-empirical molecular dynamics computation of MgO's lattice thermal conductivity at high pressures and temperatures, revealing minimal pressure effects at low pressures and expected behavior at higher pressures.

Contribution

It introduces a parameter-free, first-principles computational approach using the VIB model and Green-Kubo theory for MgO's thermal conductivity under extreme conditions.

Findings

Small pressure effect at low pressures and high temperatures

Thermal conductivity saturation due to small mean free path

Expected behavior observed at higher pressures

Abstract

The first non-empirical computation of lattice thermal conductivity has been performed for MgO using molecular dynamics (MD), a non-empirical ionic model (the Variationally Induced Breathing (VIB) model), and Green-Kubo theory. The computation is first-principles in the sense that no parameters are fit to experiment. Results are presented at low pressure as a function of temperature, and for 2500K for pressures to 290 GPa. We find an unexpectedly small pressure effect at small compressions, perhaps due to saturation of thermal conductivity at the high temperatures due to the small mean free path. At higher pressure expected behavior is found.