Ab initio molecular dynamic simulation on the elasticity of Mg₃Al₂Si₃O₁₂ pyrope

Abstract

We calculated thermo-elastic properties of pyrope (Mg₃Al₂Si₃O₁₂) at mantle pressures and temperatures using Ab initio molecular dynamic simulation. A third-order Birch-Murnaghan equation at a reference temperature of 2 000 K fits the calculations with bulk modulus, K ₀=159.5 GPa, K ₀′=4.3, V ₀=785.89 ų, Grüneisen parameter, γ ₀=1.15, q=0.80, Anderson Grüneisen parameter δ _T=3.76 and thermal expansion, α ₀=2.93×10⁻⁵ K⁻¹. Referenced to room temperature, where V ₀=750.80 Å₃, γ ₀ and α ₀ become 1.11 and 2.47×10⁻⁵ K⁻¹. The elastic properties of pyrope are found to be nearly isotropic at transition zone conditions.

Keywords

AIMD / thermo-elasticity / pyrope / high pressure

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