HR: 08:15h
AN: V51D-02    [Abstracts]
TI: Molecular Dynamics Simulation of the Structural and Physical Properties of Silicate Melts in the CaO-MgO-Al$_{2}$O$_{3}$-SiO$_{2}$ System
AU: * Matsui, M
EM: m.matsui@sci.u-hyogo.ac.jp
AF: University of Hyogo, Earth Sciences, School of Science, Kouto, Kamigori, Hyogo, 678-1297 Japan
AB: Molecular dynamics (MD) simulation is used to calculate the structural and physical properties of both crystals and silicate melts in the CaO-MgO-Al$_{2}$O$_{3}$-SiO$_{2}$ (CMAS) system. A key component of numerical computations is the reliability and applicability of interatomic potentials used for simulation. In a previous publication (Matsui, 1996) we computed the properties of various silicate melts using the MD simulation with a rather simple rigid-ion model. An improved potential model incorporating many-body forces is developed in this study, in which each oxygen ion is allowed to deform isotropically under the effects of other ions in the system concerned, as reported by Matsui (1998; called breathing-shell model, BSM). Required energy parameters, including the net charges, repulsive radii, van der Waals coefficients of ions, and the oxygen breathing parameters, were derived empirically to reproduce not only the observed structures and bulk moduli of crystals in the CMAS system, but also the measured volumes of silicate melts in the CMAS system. The MD simulation with BSM is found to be quite successful in reproducing well these measured properties of both crystals and melts. The MD simulation is further used to predict the temperature-pressure-volume equations of state and structural details of silicate melts in the CMAS system over wide temperature and pressure ranges.
DE: 8124 Earth's interior--composition and state (old 8105)
DE: 3640 Igneous petrology
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3949 Thermal expansivity
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting