Angle dependent intermolecular potential energy surfaces suitable for use in studies of rotationally inelastic collisions of rigid linear CO2 with Ar and He are calculated using the electron gas model to obtain the short range interactions and joining them smoothly to the long range van der Waals tails of the preceding paper. Smooth analytic fits to the potentials, convenient for use in scattering calculations, are given. The surfaces are very strongly nonspherical. Virial coefficients calculated using the a priori He–CO2 potential are in excellent agreement with experiment, and a simple adjustment of the Ar–CO2 potential gives excellent agreement with both virial coefficients and a potential inferred from high energy scattering data.

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Formulas are derived for the van der Waals Cn coefficients for the interaction of a diatomic molecule in a Π electronic state with an S-state atom. Two triatomic states arise from the degenerate Π state. The average of the two energies has the usual Legendre polynomial (PL) angular dependence, but the difference in energies of the two states is shown to have associated Legendre polynomial (PML with M=2) angular dependence. Procedures for including spin orbit coupling are included, and the extension to interactions of Δ- and Φ-state molecules is discussed. Values of the spherical part of the C6 coefficients for the interaction of NO with He, Ne, Ar, Kr, Xe, H, Li, Na, K, Rb, Cs, H2, N2, O2, CO, CO2, and NO are obtained from frequency-dependent polarizability data using Padé approximants. In addition, estimates of all the induction and angle-dependent parts of C6 are given for the NO–atom interactions.

Angle dependent intermolecular potential energy surfaces for the two states (2A′ and 2A″) that arise from the interaction of ground (X 2Π) state NO with Ar are calculated using the electron gas model to obtain the short range interactions. The average and difference of the two interaction energies are fit to analytic forms convenient for use in scattering calculations and joined smoothly onto the long range van der Waals potential previously determined. The results, which appear to be of useful accuracy, and the applicability of the electron gas model to such open shell–closed shell interactions are discussed.