Collaborative Research: Quantum Mechanical Modeling of Major Mantle Materials

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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.