Low Temperature Physics: 37, 445 (2011); https://doi.org/10.1063/1.3597613 (5 pages)
Ab initio calculations of three-body interaction in cryocrystals under pressure
Ie.Ie. Horbenko2, I.V. Zhikharev1,2, E.P. Troitskaya1, Val.V. Chabanenko1, and N.V. Кuzоvоi1
1Galkin Donetsk Institute for Physics and Engineering of the National Academy of Sciences of Ukraine 72 Luxemburg Str., Donetsk 83114, Ukraine
2Luhansk Taras Shevchenko National University, 2 Oboronna Str., Luhansk 91011, Ukraine
Received January 31, 2011
Short-range many-body forces obliged to the overlapping of electron shells of atoms are investigated. The requirement for the wave functions neighbor atoms of crystal to be orthogonal adds summands to the potential energy, which depend on coordinates of tree, four, etc. nearest atoms. An expression has been derived in the Hartree–Fock approximation for the electron subsystem energy of the crystal, in the basis of atomic orbital’s strictly orthogonalized at different crystal sites. The short-range three-body potential is calculated from the first principles, a simple form of the potential is proposed. The three-body forces, originating from the wave-function orthogonalization, change the run of dispersion curves for every k, violating, in particular, the Cauchy relation. Theoretical and experimental deviation from the Cauchy relation is in good agreement for Ar in a wide pressure range.
PACS: 62.50.–p High-pressure and shock wave effects in solids and liquids;
Key words: rare-gas crystals, high pressure, manybody interaction, equation of state, elastic moduli, Cauchy relation.