Elastic properties of compressed crystalline Ne in the model of deformable atoms

An ab initio version of the model with deformable atoms has been constructed to investigate the elastic properties of compressed crystalline neon. Approximations for the calculating parameters of quadrupole deformation of atomic electron shells have been discussed. It has been shown that the pressure dependence of the deviation from the Cauchy relation $\delta$ is the result of two competitive interactions, namely, the many-body and electron-phonon interactions, which manifests itself in the deformation of atomic electron shells during the shift of nuclei. In the case of Ne, contributions of these interactions are compensated to a large degree, which provides a weakly pressure-dependent positive value for $\delta$. The agreement of calculated elastic moduli and deviations from the Cauchy relation for Ne with the experiment is good.