PHONONS AND ZERO-POINT ENERGY IN THE COMPRESSED NEON CRYSTAL
A dynamic matrix of rare-gas crystals is constructed on the basis of a nonempirical shortrange repulsion potential with taking into account the three-body interaction and dipole-type deformation of the electron shells of atoms in the two- and three-body approximations in the model of deformable and polarizable atoms. Ab initio calculations of the phonon energy for the compressed Ne crystal have been performed at the points of the main value of the Chadi-Cohen method in a wide pressure range. It is shown that the contribution of three-body forces associated with the overlap of the electron shells of nearestneighbor atoms in the phonon frequencies is small against the background of pair interaction, even at high pressure. The contribution of the deformation of the electron shells in the two- and three-body approximations is different for the different mean-value points and increases with increasing pressure. There is a good agreement for the zero-point energies calculated by the Chadi-Cohen method in the Ne crystal with the available experimental data at p = 0.