Structure and elasticity of hydrous ringwoodite: A first principle investigation

The calculated bulk modulus decreases linearly with increasing water content with dK/d(CH2O)=−7.1(GPa/wt%) at room pressure, decreasing to −6.0 (GPa/wt%) at 20 GPa. The shear modulus similarly demonstrates a decrease with increased water content given, averaged over the substitution models, by dG/d(CH2O)=−3.0(GPa/wt%) at room pressure, decreasing to −1.8 (GPa/wt%) at 20 GPa. Over this pressured range, the water induce variation of d ln(VS)/d ln(VP) is 0.62 at 0 GPa to 0.2 at 20 GPa.