Dimers of rare gas atoms: CCSD(T), CCSDT and FCI calculations on the (He)_2 dimer, CCSD(T) and CCSDT calculations on the (Ne)_2 dimer, and CCSD(T) all-electron and pseudopotential calculations on the dimers from (Ne)_2 through (Xe)_2

摘要

Rare gas atom dimers from (He)_2 to (Xe)_2 were studied by beyond Hartree-Fock methods and the results obtained were compared with experimental values. In the case of (He)_2, the CCSD(T), CCSDT, and FCI results enable estimation of the role of triple and quadruple excitations. CCSD(T) already yields reliable stabilization energy values. Passing from CCSD(T) to CCSDT leads to only a small increase in the stabilization energy; a very similar value was surprisingly obtained for the (Ne)_2 dimer. For the (Ne)_2 and (Ar)_2 dimers, the all-electron and the effective core potential (ECP) results were compared. Correcting the ECP CCSD(T) characteristics for (Kr)_2 and (Xe)_2 by the factors found for (Ne)_2 and (Ar)_2 resulted in very good agreement with the experimental values.