Ab initio simulation on thermodynamic equation of state of fcc aluminum under high temperature and pressure

Abstract

The ab initio electronic structure optimization and total-energy calculations are used to study the equation of state （EOS） and elastic properties of fcc aluminum at zero temperature. We use the calculated energy of a solid as a function of the molecular volume fitting to the quasi-harmonic Debye model to obtain the non-equilibrium Gibbs function, then to derive the thermal equation of state （EOS） of the corresponding phase. The melting curve at different pressures is presented based on the Burakovsky-Preston-Silbar （BPS） model. All total-energy calculations are based on the average of local density approximation （LDA） and general gradient approximation （GGA）. The results show that the calculated EOS and pressure dependence of thermodynamics and melting curve are in good agreement with the shock compression and the diamond-anvil-cell （DAC） data within a wide range of pressure up to 225 GPa.