Thermodynamic properties calculation for MgO–SiO2 liquids using both empirical and first-principles molecular simulations

Abstract

Both classical molecular dynamics simulations and first-principles molecular simulations were carried out to investigate the thermodynamic properties of MgO-SiO(2) melts at 4000 K and 0 GPa. After equilibrating both the mini-sized and large-sized systems using classical molecular dynamics simulations, several properties and structures were calculated and compared. Consistencies were found between results from mini-sized systems and those from large-sized systems. The first-principles molecular dynamics simulations were continued for 6 ps from several independent configurations output from the mini-sized systems. The enthalpy of mixing was calculated, and results were compared with those from empirical molecular simulations. We found that first-principles simulation modified the thermodynamic properties of silicate melts, and led to positive enthalpy of mixing at high SiO(2) concentrations and negative ones at low SiO(2) concentrations. Regressing data using the Margules equation led to results consistent with available references.