MgO高温高压特性及相变的第一性原理研究

应用第一性原理密度泛函理论计算了MgO在零温(0K)下和0~200GPa静水压范围内的晶体结构和弹性模量，以及B1、B4和B8相结构的MgO的声速随压力的变化。利用准简谐近似下的Debye模型，通过拟合三阶Birch-Murnaghan物态方程模拟了高温效应并对三个相在高温高压下的相稳定性做了研究。本工作的计算结果与前人的理论和实验结果符合较好，说明第一性原理结合准简谐Debye模型能够比较准确的模拟矿物如MgO在高温高压下的热力学性质。

First-principles study of high-pressure and high-temperature behaviors and phase transition of periclase

The high-pressure and/or high-temperature behavior and phase transition of periclase (MgO) were investigated by first principle calculations with density theory (DFT), and the quasi-harmonic Debye model in consideration of the temperature effect. At zero pressure and temperature, the calculated values of lattice parameters and elastic constants are well concordant with experimental data. We calculated the wave velocity in B1, B4 and B8 phases at 0K with increasing pressure. We validated the reliability of Debye model in simulating the temperature effect and investigated the stability of the three phases in high pressure and temperature. Thus, the present results indicate that combination of first-principles and quasi-harmonic Debye model is a comparative efficient approach to simulate the partial behavior of minerals at high pressure and/or high temperature.