First-principles study of the melting temperature of MgO

Using first principles only, we calculate the melting point of MgO, also called periclase or magnesia. The random phase approximation (RPA) is used to include the exact exchange as well as local and nonlocal many-body correlation terms, in order to provide high accuracy. Using the free energy method, we obtain the melting temperature directly from the internal energies calculated with DFT. The free energy differences between the ensembles generated by the molecular dynamics simulations are calculated with thermodynamic integration or thermodynamic perturbation theory. The predicted melting temperature is TmRPA=3043±86K and the values obtained with the PBE and SCAN functionals are TmPBE=2747±59K and TmSCAN=3032±53K.