Collaborative Research: Quantum Mechanical Modeling of Major Mantle Materials

翻译由地震构造或捕虏体揭示的深层地质过程的记录，需要对高压和高温下矿物的基本物理、化学和原子尺度结构有复杂的了解。在他们之前的合作项目中，研究人员开发了一种基于密度泛函理论的地幔物质研究新方法，这是对矿物物理学实验工作的补充。他们已经证明，理论可以提供对物质行为基本原理的洞察，这些基本原理构成了我们从必然有限的实验或理论结果中插入和推断复杂地球的能力的基础。研究人员过去对纯端元相的研究预测了一些特性，这些特性为了解地球内部的本质提供了重要的新见解。在这个建议中，他们倾向于通过相变和化学交换来考虑地幔矿物之间的相互作用。本研究将首次采用从头算方法对地幔固溶体的结构、热化学、物理性质和相平衡进行理论研究。研究人员还将继续确定方向，包括预测热弹性性质。本研究将有助于我们理解：1)通过预测温度和成分对下地幔条件下Mg-Ca-Al-Fe钙钛矿等固溶体弹性性质的影响，揭示地幔横向非均质性的起源。2)地震“不连续”的成因、结构和地球动力学后果，通过预测单组分和多组分相平衡，包括钾钛矿到钙钛矿的转变，以及伪二元环木矿到钙钛矿+镁武矿的转变。3)通过预测钙钛矿的相平衡和主要共存相之间的元素分配，包括Mg-Ca分配和溶出，解释可能的过渡带和下地幔起源样品。

EAR-0230154Lars StixrudeTranslating the record of deep-seated geological processes as revealed by seismic structure or xenoliths requires sophisticated knowledge of the essential physics, chemistry, and atomic scale structure of minerals at high pressures and temperatures. Over the course of their prior collaborative project, the investigators have developed a new approach to the study of mantle materials based on density functional theory that is complementary to experimental efforts in mineral physics. They have shown that theory can provide insights into the fundamentals of material behavior that form the basis of our ability to interpolate among and extrapolate from necessarily limited experimental or theoretical results to a complex earth. The investigators past studies of pure end-member phases have predicted properties that have lent important new insight into the nature of the earth's interior. In this proposal, they move toward considering the interaction between mantle minerals through phase transitions and chemical exchange.This research will pursue for the first time with ab initio methods the theoretical investigation of mantle solid solutions, including their structure, thermochemistry, and physical properties, and of phase equilibria,. The investigators will also continue with established directions including the prediction of thermoelastic properties. This research is expected to contribute to our understanding of: 1) The origins of lateral heterogeneity in the mantle, through predictions of the effects of temperature and composition on the elastic properties of solid solutions, including Mg-Ca-Al-Fe perovskite at lower mantle conditions. 2) The origin, structure, and geodynamical consequences of seismic "discontinuities", through predictions of one-component and multi-component phase equilibria including the akimotoite to perovskite transition, and the pseudobinary ringwoodite to perovskite plus magnesiowustite transition. 3) The interpretation of samples of possible transition zone and lower mantle origin, through predictions of phase equilibira and element partitioning among major coexisting phases, including Mg-Ca partitioning and exsolution in silicate perovskite.