Collaborative Research: Quantum Mechanical Modeling of Major Mantle Materials

翻译地震构造或捕虏体揭示的深层地质过程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深入的了解。在之前的合作项目中，研究人员开发了一种基于密度泛函理论的地幔材料研究新方法，该方法与矿物物理学的实验工作相辅相成。他们已经表明，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值和外推到复杂地球的能力的基础。研究人员过去对纯端元相的研究已经预测了一些性质，这些性质对地球内部的性质提供了重要的新见解。在这一建议中，他们转向考虑地幔矿物之间通过相变和化学交换的相互作用。本研究将首次采用从头算方法对地幔固溶体的结构、热化学和物理性质以及相平衡进行理论研究。 研究人员还将继续既定的方向，包括热弹性性质的预测。通过预测温度和成分对下地幔Mg-Ca-Al-Fe钙钛矿等固溶体弹性性质的影响，探讨地幔横向不均匀性的起源。2)地震“不连续性”的起源、结构和地球动力学后果，通过单组分和多组分相平衡的预测，包括akimotoite到钙钛矿的转变，以及伪二元ringwoodite到钙钛矿加镁橄榄石的转变。3)通过预测主要共存相之间的相平衡和元素分配，包括硅酸盐钙钛矿中的Mg-Ca分配和出溶，解释可能的过渡区和下地幔起源的样品。

EAR-0230319WentzcovitchTranslating 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.--