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A quantum-mechanical study of the relative stability under pressure of MgSiO3-ilmenite, MgSiO3-perovskite, and MgO-periclase+SiO2-stishovite assemblage by Ph. D'Arco; G. Sandrone; R. Dovesi; E. Aprà; V. R. Saunders is a Materials Science article available to read on EtoBox.

What is A quantum-mechanical study of the relative stability under pressure of MgSiO3-ilmenite, MgSiO3-perovskite, and MgO-periclase+SiO2-stishovite assemblage about?

The relative stability of MgSiO3-ilmenite , MgSiO3-perovskite and (periclase+stishovite) assemblage phases as a function of the pressure is investigated with the periodic quantum mechanical ab initio Hartree-Fock program CRYSTAL. For the first time, the structure of MgSiO3-ilmenite is fully optimized. Basis set effects are explored. It turns out that relatively small basis sets reproduce correctly experimental geometries. However, larger basis sets (" triple zeta" quality, plus polarization d functions) are needed to yield significant thermochemical results. All contributions to the 0 K enthalpy are discussed. On the basis of the present highest level calculations, it appears that in the explored range of pressure (0 < P < 60 GPa) the mineralogical assemblage peri-clase+stishovite has higher enthalpy than MgSiO3-ilmenite or perovskite, and that ilmenite transforms to orthorhombic perovskite around to 29.4 GPa in good agreement with experimental data extrapolated down to OK.

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Author

Ph. D'Arco; G. Sandrone; R. Dovesi; E. Aprà; V. R. Saunders

Publisher

Springer-Verlag; Springer Verlag; Springer Science and Business Media LLC; Society for Mining, Metallurgy and Exploration Inc.; Springer Nature (ISSN 0342-1791)

Published

1994

Language

EN

Field

Materials Science (Physical Sciences)