AB-INITIO CONFORMATIONAL STUDY OF THE CO - H2 VAN-DER-WAALS DIMER

Quantum chemical fully ab initio conformational calculations were perf ormed for the weakly bound van der Waals CO...H2 dimer in the framewor k of the supermolecule approach. The counterpoise-corrected interactio n energies, computed through fourth-order MBPT using the basis sets de scribed recently by Sadlej, were in excellent agreement with results o btained with larger basis sets constructed to give accurate values for the electric moments and polarizabilities of CO and H2. The relative stability of the configurations studied here was collinear structures > parallel structure > T-shaped structures. The collinear and parallel structures represent the most stable group of configurations. The pre sent calculations show that they have values of D(e) between 5.89 and 10.66 meV. The T-shaped structures represent relatively less stable co nfigurations with values of D(e) between 0.84 and 2.92 meV. (C) 1995 J ohn Wiley & Sons, Inc.