在這個三年計劃中，我們將使用第一原理計算研究地球及行星內部物質在極端條件下的性質。我們建議研究三種類型的物質，在地球物理、地球化學、及行星科學上各有其重要性。首先是含鐵碳酸鹽在下地函的行為。一般相信，含鐵碳酸鹽是下地函中最主要的攜碳礦物，也在地球深部碳循環中扮演重要角色。然而，含鐵碳酸鹽在下地函的高壓下會產生複雜的相變，至今我們們仍然不清楚含鐵碳酸鹽在 100 GPa 之後的原子結構與及其物理及化學性質。藉由第一原理計算，我們希望能夠闡明含鐵碳酸鹽系統在高壓下的行為，並進一步理解地球的深部碳循環。我們打算研究的第二類物質是系外類地行星內部含鐵的鎂矽氧系統，及其在超高壓 (TPa) 之下的行為。相似於地球，系外類地行星內部的主要組成也是鎂、矽、氧、鐵，但在系外行星內部的超高壓之下，具體的礦物相及其性質仍然不明。藉由研究超高壓之下的物性，有助於我們進一步瞭解系外類地行星的演化及內部結構。我們打算研究的第三類物質是隱沒板塊裡的礦物。這方面的研究，將有助我們更進一步瞭解隱沒板塊最終的結局，及其對地函動力學及地函不均勻性的影響。 ;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.
