Structural and elastic anisotropy of crystals at high pressures and temperatures from quantum mechanical methods: The case of Mg{sub 2}SiO{sub 4} forsterite

Journal Article · Thu May 28 00:00:00 EDT 2015 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4921781· OSTI ID:22415875

Dovesi, R. ^[1]; Maul, J. ^[1]; De La Pierre, M. ^[2]

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1. Dipartimento di Chimica and Centre of Excellence NIS (Nanostructured Interfaces and Surfaces), Università di Torino, via Giuria 5, IT-10125 Torino (Italy)
2. Nanochemistry Research Institute, Curtin Institute for Computation, Department of Chemistry, Curtin University, GPO Box U1987, Perth, WA 6845 (Australia)

We report accurate ab initio theoretical predictions of the elastic, seismic, and structural anisotropy of the orthorhombic Mg{sub 2}SiO{sub 4} forsterite crystal at high pressures (up to 20 GPa) and temperatures (up to its melting point, 2163 K), which constitute earth’s upper mantle conditions. Single-crystal elastic stiffness constants are evaluated up to 20 GPa and their first- and second-order pressure derivatives reported. Christoffel’s equation is solved at several pressures: directional seismic wave velocities and related properties (azimuthal and polarization seismic anisotropies) discussed. Thermal structural and average elastic properties, as computed within the quasi-harmonic approximation of the lattice potential, are predicted at high pressures and temperatures: directional thermal expansion coefficients, first- and second-order pressure derivatives of the isothermal bulk modulus, and P-V-T equation-of-state. The effect on computed properties of five different functionals, belonging to three different classes of approximations, of the density functional theory is explicitly investigated.

• OSTI ID: 22415875
• Journal Information: Journal of Chemical Physics, Vol. 142, Issue 20; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
APPROXIMATIONS
DENSITY FUNCTIONAL METHOD
ELASTICITY
EQUATIONS OF STATE
FLEXIBILITY
MAGNESIUM SILICATES
MELTING POINTS
MINERALS
MONOCRYSTALS
ORTHORHOMBIC LATTICES
PHASE DIAGRAMS
POLARIZATION
PRESSURE DEPENDENCE
QUANTUM MECHANICS
SEISMIC WAVES
TEMPERATURE DEPENDENCE
THERMAL EXPANSION