Melting of MgO studied using a multicanonical ensemble method combined with a first-principles calculation

TL;DR

This paper presents a novel multicanonical ensemble method combined with first-principles calculations to study MgO melting, capturing pressure dependence and thermodynamic properties with a simple model potential.

Contribution

It introduces a new approach integrating multicanonical ensemble with first-principles calculations and auxiliary degrees of freedom for melting studies.

Findings

Pressure dependence of melting point matches previous simulations

Latent heat and volume change are consistent with prior computational results

Method distinguishes effects of different exchange-correlation potentials

Abstract

Melting of MgO was studied using a multicanonical ensemble method combined with a first-principles calculation. This approach has been successively performed by using a rather simple functional form for a model inter-atomic potential that is determined from first-principles and a novel approximation treating auxiliary degrees of freedom, such as electron thermal excitations, within a multicanonical ensemble method. Although a rather simple model potential was used, this approach could distinguish differences due to the exchange-correlation potential used in the first-principles calculations. The pressure dependence of the melting point, latent heat, and volume change during melting were studied. The obtained dependence was similar to that reported by Alfe which differs from experimental results. This dependence did not change even with the PBEsol exchange-correlation potential.