Ab initiothermodynamics of MgSiO3 perovskite at high pressures and temperatures

Using quantum-mechanical simulations based on density-functional perturbation theory, we address the problem of stability of MgSiO3 perovskite to decomposition into MgO and SiO2 at pressures and temperatures of the Earth’s lower mantle. We show that MgSiO3 perovskite (and its post-perovskite phase) is more stable than the mixture of oxides throughout the pressure-temperature regime of the Earth’s mantle. Structural stability and lattice dynamics of phases in the system MgO-SiO2 are discussed.