Toward an accurate description of rare gas phases

Full text: Rare gas solids provide an ideal testing ground for the accurate many-body treatment of electron correlation through a many-body decomposition of the interaction potential. Here we present complete basis set (CBS) limit calculations for the fcc lattices of solid neon and argon, using second- to fourth-order Møller-Plesset theory, MP2-4, and coupled-cluster calculations, CCSD(T), to describe electron correlation within a many-body expansion of the interaction potential up to third order. A correct description of the three-body Axilrod-Teller-Muto term for the solid state is only obtained from third-order on in the many-body expansion of the correlation energy, correcting the severe underestimation of long-range three-body effects at the MP2 level of theory. The dilemma that all two-body interaction potentials prefer the hcp over the fcc structure is discussed. The performance of the methods with increasing pressure is analyzed, showing that the convergence of the Møller-Plesset series deteriorates as the electronic band gap decreases, resulting in rather large deviations for the equation of state (pressure-volume dependence). The application to the accurate determination of melting temperatures at high pressures is discussed. (author)