First-principles study of the elastic and thermodynamic properties of CaSiO3 perovskite

The thermodynamic and elastic properties of CaSiO3 perovskite are investigated at high pressures and temperatures using the plane wave pseudopotential method within the local density approximation. The athermal elastic moduli of CaSiO3 perovskite are calculated as a function of pressure up to 200 GPa. The calculated results are in excellent agreement with available experimental data at high pressure, and compare favourably with other pseudopotential predictions over the pressure regime studied. It is also found that the elastic anisotropy drops rapidly with the increase of pressure initially, and then decreases more slowly at higher pressures. The thermodynamic properties of CaSiO3 perovskite are predicted using the quasi-harmonic Debye model for the first time; the heat capacity and the thermal expansion coefficient agree with the observed values at ambient conditions and the other calculations at high pressures and temperatures