MgSiO_3钙钛矿高温高压特性的第一性原理研究

First-principles simulations of thermoelastic properties of MgSiO_3-perovskiite at high temperature and high pressure

本文采用第一性原理方法,计算了MgSiO_3钙钛矿在零温和0～150 GPa静水压范围内的晶体结构和弹性模量,并利用准简谐近似Debye模型,拟合三阶Birch-Murnaghan物态方程得到了其高温高压下的热力学性质.通过与现有的理论和实验的结果数据比较,确认在0～2000K的温度区间内,第一性原理计算结合Debye模型能够较可靠地模拟在下地幔压力范围内MgSiO_3钙钛矿的热力学性质.

The crystal structures and elastic properties of MgSiO3 perovskite in a range of hydrostatic pressure from 0 GPa to 150 GPa have been investigated using density functional theory （DFT）, and their thermodynamic quantities at high temperature and high pressure have been computed by means of a Debye model within the quasi-harmonic approximation ,The P-V data at different temperatures were fitted to the third-order Birch-Murnaghan equation of states. By comparing our present results with previous theoretical calculations and experimental data, it is demonstrated that the high-pressure elastic properties of MgSiO3 perovskite in the condition of lower mantle can be described using the quasi-harmonic Debye model combined with first-principles calculations.