Collaborative Research: First Principles Investigation of Silicate Liquids at Mantle Conditions

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The project will apply the first-principles approach based on density functional theory (DFT) to investigate the physico-chemical properties of silicate liquids, which are major components of the Earth's mantle. The approach has already been proven to be an ideal complement to the experimental approach in studying a wide range of crystalline properties of the Earth materials and here it will be extended to simulation of material systems involving relative large number of atoms. These large-scale simulations will result in major advances in our knowledge of silicate liquids over the large range of pressure, temperature, and composition that are crucial for a better understanding of planetary evolution, as silicate liquids are primary means of heat and mass transport inside the Earth. The project will make key contributions to understanding of: a) Buoyancy of silicate liquids through ab initio predictions of the equation of state including liquids of diopside, enstatite, and forsterite compositions over the pressure-temperature regime of the mantle; b) Structure of silicate liquids via analysis of the complete structural information that is available in theoretical simulations including coordination numbers, bond lengths, and bond angles. Analysis of the structure of liquids of diopside and hydrous albite composition, and melts on the MgO-SiO2 join is expected to yield insight into the origin of melt behavior including compression mechanisms and mixing properties; and c) Thermodynamics of mixing in silicate liquids through ab initio predictions of the volume and enthalpy of mixing as a function of composition along the MgO-SiO2 and albite-water joins. The proposed research is essentially an exploitation of ideas and techniques of computational science to challenging problems in the investigation of Earth materials. The cross-fertilization between studies of complex geochemical and earth materials issues on the one hand, and high-end computation on the other should be of benefit to both fields. To take full advantage of this aspect, the project will also initiate applications of the Access Grid - a facility that allows group-to-group multimedia network communication, to train students in this interdisciplinary effort.