van der Waals Constants and Nonadditive Triple-Dipole Force Constants for He and Ne by the Coupled Hartree-Fock Approximation

The dynamic polarizability and the dipole shielding factor at imaginary frequencies are calculated for He and Ne by the coupled Hartree-Fock approximation. The integrodifferential equations for the perturbed wavefunctions are solved numerically without use of the variational procedure. By using Casimir-Polder type formulas, the van der Waals constants μ and the nonadditive triple-dipole force constants ν are computed for He and Ne. Results (in atomic units) are μHeHe=1.38, μHeNe=2.71, μNeNe=5.44, νHeHeHe=1.33, νHeHeNe=2.51, νHeNeNe=4.76, and νNeNeNe=9.10.