Abstract
A computational model of a crystal consists of a description of the structure, a potential function for calculating its energy, and a way of adjusting the structure to minimize the calculated energy. External forces such as hydrostatic pressure or normal and shearing stresses can be simulated, and elastic constants can be calculated. A realistic model should reproduce both the experimental structure and the observed elastic properties.
Such a model has been developed for α Mg2SiO4, the olivine orthosilicate known as forsterite. Coulomb energy is calculated for a structure consisting of Mg2+ ions and rigid SiO 4−4 groups with partial charges on Si and O atoms. Both r −n and exponential expressions were tried for the repulsion energy, and the latter expression yields the best results. This model reproduces reasonably well the experimental structure, the observed elastic constants, and their pressure derivatives. The same model successfully describes γ Mg2SiO4, the cubic spinel polymorph related to ring-woodite. Comparison is made with similar calculations by other authors.
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Research sponsored by the Division of Materials Sciences, Office of Basic Energy Sciences, U.S. Department of Energy, under contract W-7405-eng-26 with the Union Carbide Corporation
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Matsui, M., Busing, W.R. Computational modeling of the structure and elastic constants of the olivine and spinel forms of Mg2SiO4 . Phys Chem Minerals 11, 55–59 (1984). https://doi.org/10.1007/BF00308005
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DOI: https://doi.org/10.1007/BF00308005