Complex Materials under Extreme Conditions in the Earth and Exoplanet Interiors(3/3)

In this three year project, we plan to use first-principles calculations to study Earth and planetary materials under extreme conditions. We propose to investigate three categories of materials for their importance in geophysics, geochemistry, and planetary science. The first category of materials is iron-bearing carbonates in the Earth's deep lower mantle. While iron-bearing carbonates are believed to be the major carbon carrier in the Earth's deep interior and play a key role in the Earth's deep carbon cycle, the complicated structural transition and the stable phase of carbonate beyond 100 GPa are still remain unclear, let along their physical and chemical properties. By combing first-principles structure search and LDA+Usc method, our research can shed light on the complicated (Mg,Fe)CO3 system and provide valuable insight to the Earth's deep carbon cycle. The second category is Fe-bearing Mg-O and Mg-Si-O systems in the deep interior of terrestrial-type exoplanets, where the pressure range is in the TPa regime. Similar to the Earth, terrestrial-type exoplanets also consist of Mg, Si, and O, with a significant amount of Fe, but the mineral phases and their properties under the ultrahigh pressure in the exoplanet interior are still unknown. By studying materials properties at ultrahigh pressure, we can better understand the evolution and interior of exoplanets. The third category is minerals in the subducted mid-ocean ridge basalt (MORB). Knowledge of minerals in this region of the Earth can help us fully understand the fate of subducted MORB and its effects on mantle dynamics and mantle heterogeneity.