COUPLED-PAIR FUNCTIONAL CALCULATIONS ON THE AR-CO AND AR2 VAN-DER-WAALS COMPLEXES

After an assessment of the equilibrium properties of Ar2 (D(e) almost-equal-to 75 cm-1, R(e) almost-equal-to 7.32 bohr) as determined in supermolecular coupled-pair functional calculations in the limit of high angular momentum basis functions, the potential energy surface for interaction of an Ar atom with the CO molecule is presented. The calculated potential energy surface has its absolute minimum of D(e) = 71 cm-1 at a T-shaped geometry. The barriers for rotation around the oxygen and carbon end of the complex have been found to be 13 and 21 cm-1, respectively. The performance of averaged coupled-pair functional and averaged quadratic coupled-cluster techniques for calculation of interaction energies of Ar2 and Ar-CO and for determination of electrostatic moments and polarizabilities of the CO molecule is briefly discussed as well.