POTENTIAL ENERGY SURFACE FOR THE $H_{2}$-CO VAN DER WAALS COMPLEX

$^{1}$ A.R.W. McKellar. J. Chem. Phys. 93 , 18 (1990) $^{2}$ A.R.W. McKellar, Chem. Phys. Lett. 186 , 58 (1991). $^{3}$ R. Schinke, H. Meyer, U. Buck and G.H.F. Dierksen J. Chem. Phys. 80 , 5518 (1984).Author Institution: Guelph-Waterloo Centre for Graduate Work in Chemistry, University of WaterlooFully-resolved infrared spectra of the weakly bound diatom-diatom Van der Waals complexes $H_{2}$-Co and $D_{2}$-Co have recently been reported by $McKellar.^{1,2}$ Because of the large rotational level spacing and near-spherical nature of diatomic hydrogen, the energy level patterns of $H_{2}(j=0)-Co$ complexes are almost identical to those formed between the CO diatom and a structureless atom. Consequently, our preliminary non-linear least squares fits to the observed transition frequencies and predissociation line widths for para $H_{2}$-Co and ortho $D_{2}$-Co (simultaneously) were used to determine a 3-dimensional potential energy surface which depends on the intermolecular separation, on the relative orientation of the CO, and on the CO bond length. As was the case for He-Co (preceeding abstract), this surface yilded intensity pattems in good agreement with experiment, but predictions based on the ab initio potential of Schinke $et al^{3}$ had substantial weaknesses. In continuing work, this analysis is being extended to the significantly more complex ortho $H_{2}$-CO and para $D_{2}$-CO spectra, which also depend on the orientation of the $H_{2}$ or $D_{2}$ relative to both the CO and the intermolecular axis