Hartree--Fock and Gordon--Kim interaction potentials for scattering of closed-shell molecules by atoms: (H2CO,He) and (H2,Li+)

The Gordon--Kim (GK) electron gas model for calculating the forces between closed-shell atoms and molecules is applied to the He--H2CO and Li+--H2 systems. GK interaction energies are computed following the original theory and also including the self-energy correction suggested by Rae. GK interaction energies, neglecting correlation, are found to be in qualitative accord with Hartree--Fock (HF) interaction energies for the two systems. However, quantitative discrepancies are noted which are possible sources of error if GK potential energy surfaces are used to compute accurate scattering cross sections