High pressure elastic properties of solid argon from first-principles density functional and quasi-harmonic lattice dynamic calculations

The equation of states and the elastic moduli of solid argon have been calculated with a first-principles density functional method and from an empirical potential. The calculated equation of state is in excellent agreement with experiment. The predicted pressure dependence of the C44 shear modulus is also in good accord with recent measurements up to 70 GPa. On the other hand, the calculated C11 and C12 moduli are in reasonable agreement with the experiment at low pressure but start to deviate significantly from the observed values at pressure higher than 10 GPa. This discrepancy may be attributed to the non-hydrostaticity of the crystalline argon sample at high pressure.