Ab initio molecular dynamic simulation on the elasticity of Mg3Al2Si3O12 pyrope

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 (3), Gruneisen parameter, gamma (0)=1.15, q=0.80, Anderson Gruneisen parameter delta (T) =3.76 and thermal expansion, alpha (0)=2.93x10(-5) K-1. Referenced to room temperature, where V (0)=750.80 (3), gamma (0) and alpha (0) become 1.11 and 2.47x10(-5) K-1. The elastic properties of pyrope are found to be nearly isotropic at transition zone conditions.