MgSiO3 Under Conditions of the Earth's Deep Interior

MgSiO₃ phase diagram has been studied theoretically by first principles static and both ab initio and semi-empirical molecular dynamics methods. The melting curve of MgSiO₃ was obtained also by dislocation-mediated theory of melting. All methods produce a consistent phase diagram of MgSiO₃, which is calculated up to pressure of 4 Mbar. At high pressure, the diagram shows presence of three MgSiO₃ phases, namely, perovskite, so-called post-perovskite, and liquid. The diagram is in good agreement with the recent experimental data on post-perovskite phase. The MgSiO₃ melting curve is rather steep at pressures under 100 GPa while at higher pressures it has a much lower slope and lies above that of Fe by about 1000 K