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Hydrogen has been attracting much attention not only as the next generation energy recourses, but also as one of the most important elements involved in the history of earth formation. In the process of the primitive Earth formation, the Earth's surface may have been hot molten (magma ocean) and may have played an important role in the formation of the hydrosphere by storing huge amount of water (hydrogen) in it. In the present Earth, hydrogen exists as water (H2O), hydrous minerals (OH group) or other compounds as well as impurities intruded into magma and anhydrous minerals. Water (hydrogen) has a huge impact on physical properties such as structure, melting point, viscosity and reactivity of magma and minerals. Therefore the atomic-level understanding of these mechanisms plays an essential role in studying the history of Earth formation, volcanic eruption and geodynamics at deep in the Earth.
Our group applies the state of art quantum simulations to clarify the effects of hydrogen and hydrogen-bonds to the structure and properties of minerals, magma and water from the Earth’s surface to the high-temperature high-pressure area in the deep Earth. We should contribute significantly to the Innovative Area in understanding the experimental data in terms of theory as well as in improving the experimental procedures in terms of efficiency.
We have been making remarkable achievements in the field of materials science and mineralogy under high pressures by developing and using state of art quantum simulation methods such as the first principle molecular dynamics method at constant pressure and temperature, the density functional linear response theory, the first principles path integral molecular dynamics, order-N first-principle molecular dynamics, order-N tight binding molecular dynamics and first-principles crystal structure prediction methods. Applying these methods to hydrogen-containing Earth materials in cooperation with neutron scattering experimenters, we are eager to develop a new interdisciplinary field of the computational materials science and the earth and planet sciences.
We will further develop our quantum simulation techniques to understand the effects of water in the structure and properties of minerals, magma under high temperature and high pressure. In the fiscal year 2008, we set up the foundation for the five year project by constructing PC cluster for this project and installing a variety of quantum simulation program. In the fiscal years 2008-2010, when the high-pressure high-temperature neutron scattering beam line is still under construction, we promote the quantum simulations of minerals, magma and water under high-temperature and high pressure. The simulation results are to become important guidelines of the experimental groups in the research area. Specifically, three topics are focused on: stable high-pressure phases, hydrogen positions and property prediction of hydrous minerals prediction of structure, properties and melting relations of magma under high pressure structure and properties of liquid water under high pressure. In addition to the above three topics, the plastic deformation mechanism of nano-polycrystalline diamond (NPD), a candidate material for the next generation diamond anvil cell, is also studied. In the fiscal years 2011 and 2012, when the high-temperature high-pressure neutron scattering beam line is planned to be completed, we extend our research by providing the simulation outputs to experimenters and the experimental outputs to theoretical researchers.