First-principles study of MgSiO$_{3}$ at core-mantle boundary conditions

Perovskite MgSiO$_{3}$ is an important mineral in geoscience studies. It plays a crucial role in the understanding of geophysical and geochemical activities taken place in the Earth's interior. In this talk, we report our recent work on First-principles molecular dynamics (FPMD) simulations of solid MgSiO$_{3}$ perovskite and post-perovskite, and molten MgSiO$_{3}$ at core-mantle boundary (CMB) conditions. The equations of state are determined at pressures up to 200 GPa and temperatures up to 6000K. The post-perovskite phase is found to be favoured over the perovskite at pressures above 102 GPa at zero temperature. Melting of MgSiO$_{3}$ has been observed by heating both perovskite and post-perovskite at high temperatures ($\sim$6000 K). The melting curve and electronic structures of solid and molten MgSiO$_{3}$ are also presented. Our simulated results thus provide useful constraints on structure and phase stability of MgSiO$_{3}$, which is the key to the understanding of deep-earth phenomena, such as the D$''$ discontinuity and seismic anisotropies in D$''$ layer. More importantly, the phase transformation of MgSiO$_{3}$ studied in this work provides insights into other aspects of geosciences like chemical heterogeneity and mantle convection, which may lead to a better model of the Earth's evolution.