First-principles calculation of elastic properties of solid argon at high pressures

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The density and the elastic stiffness coefficients of fcc solid argon at high pressures from 1 GPa up to 80 GPa are computed by the first-principles pseudopotential method with plane-wave basis set and generalized gradient approximation (GGA). The result is in good agreement with an experimental result recently obtained with Brillouin spectroscopy by Shimizu et al. [Phys. Rev. Lett. 86, 4568 (2001)]. Solid argon becomes very hard due to its closed-shell electronic configuration. The Cauchy condition is strongly violated, indicating a large contribution from a noncentral many-body force. The present result has made it clear that the standard density functional method with periodic boundary conditions can be successfully applied for calculating the elastic properties of rare gas solids at high pressures in contrast to those at low pressures where dispersion forces are important.