An ab initio CO dimer interaction potential and the computation of the rovibrational spectrum of (CO)2

Abstract

A full potential energy surface (PES) is computed for a dimer consisting of rigid CO molecules. The coupled cluster single double plus perturbative triples [CCSD(T)] method is used with the augmented correlation consistent polarized valence triple zeta atomic orbital basis (aug-cc-pVTZ) with bond orbitals in the middle of the CO–CO bond. The PES is fitted in terms of analytic functions and the fitted potential is used to compute the lowest rovibrational states of the dimer. Semi-quantitative agreement with recent millimeter-wave experiments (M. D. Brookes and A. R. W. McKellar, J. Chem. Phys., 1999, 111, 7321–7328; D. A. Roth, L. A. Surin, B. S. Dumesh, G. Winnewisser and I. Pak, J. Chem. Phys., 2000, 113, 3034–3038 and J. Tang et al., J. Mol. Spectrosc., 2002, 214, 87–93) is found.