Coupled cluster ab initio potential energy surfaces for CO...He and CO...H-2

Ab initio potential energy surfaces including the vibrational coordinate dependence are presented for CO… He and CO… H2 using the coupled cluster method with Brueckner orbitals. The interaction energy is calculated using the supermolecule approach. The calculation of rate constants for the vibrational relaxation of CO(v = 1) by He and their comparison with the experimentally measured values over the temperature range 40–300 K is used to test the accuracy of the CO… He surface. Comparison with results from an earlier surface calculated by symmetry adapted perturbation theory shows that the two surfaces have similar scattering characteristics and reproduce the experimental measurements to a similar level of accuracy. The potential surface for the CO… H2 system is presented as raw data in anticipation of future calculations.