Elementary vibrations in rare-gas crystals: Frequencies of phonons in compressed argon, krypton, and xenon crystals

Lattice dynamics of cryocrystals at high pressure

“…This approach as applied for rare-gases crystals in the sequence Ne-Xe makes it possible to determine the most important interactions in these crystals, i.e., the structure of the interatomic potentials. For this purpose, we analyzed six models of interatomic interaction in rare-gas crystals [24,25]. It was demonstrated that the M2 model for argon, krypton, and xenon and the model M4 for neon are quite consistent; they are based on clear physical principles and well formulated approximations, and adequately describe the phonon frequencies at low pressures and temperatures.…”

“…In this study, as in [18,24,25,27], the adiabatic potential E was constructed using a general approach. This approach as applied for rare-gases crystals in the sequence Ne-Xe makes it possible to determine the most important interactions in these crystals, i.e., the structure of the interatomic potentials.…”

“…We showed in [24,25] that, as the compression ratio increases to below 0.6, the frequencies hw l ( ) k increase by approximately one order of magnitude but the phonon dispersion curves remain smooth; by contrast, the electronic spectra for the neon crystal at a compressions above 0.6 exhibit distortions and «humps». In the phonon spectrum, as it can be seen from Fig.…”

“…As in [25], the simplest model M2 corresponds to the nearest-neighbor approximation (E F = =0) without account for the nonadiabatic contributions (g h = =0) in which the potential V sr (1) is calculated in the S 2 approximation. The M3 model additionally includes the next-to-nearest neighbors.…”

Elastic properties of compressed cryocrystals in a deformed atom model

“…In the series of recent papers [27][28][29] we considered nonadiabatic effects, i.e., the electron-phonon interaction induced by the deformation of electron shells of the atoms in the dipole approximation. This corresponds to the inclusion of the lower order terms in the nonadiabaticity parameter.…”