First-Principles Study of Orthorhombic Perovskites MgSiO3 up to 120 GPa and Its Geophysical Implications  

作　　者：邓力维 赵纪军 姬广富 龚自正 魏冬青 

机构地区：[1]Institute of High Pressure and High Temperature Physics, Southwest Jiaotong University, Chengdu 610031 [2]College of Advanced Science and Technology, Dalian University of Technology, Dalian 116023 [3]Laboratory for Shock Wage and Detonation Physics, Institute of Fluid Physics, Mianyang 621900 [4]Beijing Institute of Spacecraft Environment Engineering, Beijing 100094 [5]College of Life Science and Technology, Shanghai Jiao Tong University, Shanghai 200240 [6]Center for Research in Molecular Modeling (CERMM), Concordia University, Montreal, Canada

出　　处：《Chinese Physics Letters》2006年第8期2334-2337,共4页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China under Grant Nos 40474033 and 10376024, and the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20050613017.

摘　　要：High-pressure behaviour of orthorhombic MgSiO3 perovskite crystal is simulated by using the density functional theory and plane-wave pseudopotentials approach up to 120 GPa pressure at zero temperature. The lattice constants and mass density of the MgSiO3 crystal as functions of pressure are computed, and the corresponding bulk modulus and bulk velocity are evaluated. Our theoretical results agree well with the high-pressure experimental data. A thermodynamic method is introduced to correct the temperature effect on the O-K first-principles results of bulk wave velocity, bulk modulus and mass density in lower mantle PIT range. Taking into account the temperature corrections, the corrected mass density, bulk modulus and bulk wave velocity of MgSiO3-perovskite are estimated from the first-principles results to be 2%, 4%, and 1% lower than the preliminary reference Earth model （PREM） profile, respectively, supporting the possibility of a pure perovskite lower mantle model.High-pressure behaviour of orthorhombic MgSiO3 perovskite crystal is simulated by using the density functional theory and plane-wave pseudopotentials approach up to 120 GPa pressure at zero temperature. The lattice constants and mass density of the MgSiO3 crystal as functions of pressure are computed, and the corresponding bulk modulus and bulk velocity are evaluated. Our theoretical results agree well with the high-pressure experimental data. A thermodynamic method is introduced to correct the temperature effect on the O-K first-principles results of bulk wave velocity, bulk modulus and mass density in lower mantle PIT range. Taking into account the temperature corrections, the corrected mass density, bulk modulus and bulk wave velocity of MgSiO3-perovskite are estimated from the first-principles results to be 2%, 4%, and 1% lower than the preliminary reference Earth model （PREM） profile, respectively, supporting the possibility of a pure perovskite lower mantle model.

关 键 词：EARTHS LOWER MANTLE THERMOELASTIC PROPERTIES SILICATE PEROVSKITE THERMALEXPANSIVITY MOLECULAR-DYNAMICS AB-INITIO EQUATION STATE PSEUDOPOTENTIALS COMPUTATION 

分 类 号：O7[理学—晶体学]