Ab initio intermolecular potential-energy surface and microwave spectra for the Ne-OCS complex

An ab initio potential-energy surface for the Ne-OCS complex was calculated using the coupled-cluster singles and doubles with noniterative inclusion of connected triples CCSD(T)] with a large basis set containing bond functions. The interaction energies were obtained by the supermolecular approach with the full counterpoise correction for the basis set superposition error. The CCSD(T) potential was found to have three minima corresponding to the T-shaped and the linear Ne-SCO and Ne-OCS structures. The two-dimensional discrete variable representation method was employed to calculate the rovibrational energy levels for five isotopomers Ne-OCS, (22)Ne-OCS, Ne-OC(34)S, Ne-O(13)CS, and Ne-(18)OCS. The calculated pure rotational transition frequencies for the vibrational ground state of the five isotopomers are in good agreement with the observed values. The corresponding microwave spectra show that the b-type transitions (deltaK(a)=+/-1) are significantly stronger than the a-type transitions (deltaK(a)=0).