Melting slope of MgO from molecular dynamics and density functional theory

TL;DR

This study combines density functional theory and molecular dynamics to accurately calculate the melting slope of MgO at ambient pressure, addressing a long-standing discrepancy between theory and experiment.

Contribution

It introduces a combined DFT and atomistic force field approach to resolve the longstanding disagreement on MgO's melting slope.

Findings

Reasonable agreement with recent experimental data

Discrepancy with older experiments suggests possible flaws in previous measurements

Highlights potential limitations of current density functionals

Abstract

We combine density functional theory (DFT) with molecular dynamics simulations based on an accurate atomistic force field to calculate the pressure derivative of the melting temperature of magnesium oxide at ambient pressure - a quantity for which a serious disagreement between theory and experiment has existed for almost 15 years. We find reasonable agreement with previous DFT results and with a very recent experimental determination of the slope. We pay particular attention to areas of possible weakness in theoretical calculations and conclude that the long-standing discrepancy with experiment could only be explained by a dramatic failure of existing density functionals or by flaws in the original experiment.