Collaborative Research: Quantum Mechanical Modeling of Major Mantle Materials

在这次更新中，研究人员建议继续开发和应用从头算分子动力学技术来研究地幔主要组成部分的物理性质。这里使用的主要方法包括第一原理变胞形分子动力学。这项技术是由Wentzkovitch开发的，并已成功地用于研究几个地幔相在零温下的结构和弹性性质，以及在高压和高温下二氧化硅和金属中的结构相变。这是一种新的方法，能够解决具有地球物理意义的问题，例如：1)高压晶体结构及其与压力的关系的预测，2)相变的先验预测，以及3)完全非谐的高P，T热力学性质，如热膨胀系数和弹性常数。研究人员建议将这些研究进一步扩展到更复杂和潜在重要的水合和铝相，以及包括状态方程和弹性常数在内的高温性质的研究。这项研究的目的是预测并为更严格地讨论地幔的物理和化学及其动力学提供坚实的理论基础。

9973139Stixrude In this renewal the investigators propose to continue developing and applying ab initio molecular dynamics techniques to investigate the physical properties of major constituents of the earth's mantle. The primary method used here consists of first principles variable cell shape molecular dynamics. The technique was developed by Wentzkovitch and has been successfully used to investigate structural and elastic properties of several mantle phases at zero temperature, and structural phase transitions at high pressures and temperatures in silica and metals. This is a novel approach that is capable of addressing problems of geophysical importance such as: 1) prediction of high pressure crystal structures and their pressure dependence, 2) a priori prediction of phase transitions, and 3) fully anharmonic high P, T thermodynamic properties such as thermal expansivity and elastic constants. The investigators propose to further extend these studies to more complex and potentially important hydrous and aluminous phases, and high temperature studies of properties including the equation of state and the elastic constants. The aim of this research is to predict and provide a firm theoretical basis for a more rigorous discussion of the physics and chemistry of the mantle and its dynamics.