Nonadditive three-body interactions of rare-gas atoms. II. Intermediate and large distances

The failure of the preceding paper to describe the nonadditive three-body forces at large internuclear separations is remedied by using a model developed earlier for the pair interactions by the present author and Gordon. The model includes descriptions of both the long-range forces, which are based on a harmonic-oscillator model for atoms, and the short-range forces with their effect on the long-range forces. The results give predictions of the nonadditive three-body forces for the entire portion of the physically interesting region of the potential surfaces. We find that the nonadditive contributions are a few percent or less of the total interaction over most ranges of internuclear separation.