Ab initio study of the Ne(1S)-CN(2Σ+) van der Waals complex

The Ne(S-1)-CN((2)Sigma(+)) van der Waals complex, described by Jacobi coordinates (R, -), was studied using the supermolecular and perturbation UHF as well as RHF ab initio treatments with the inclusion of correlation energy. The computed potential energy surface at the restricted MP2 level of the theory reveals a single minimum, located near the T-shaped configuration at - = 110 degrees, R = 3.7 Angstrom, and its well depth amounts to -145.9 mu E-h When compared with the RMP2 potential, the UMP2 surface is more repulsive in the region of the minimum and the double-well character of the angular-dependent potential curves appears about R approximate to 3.7 Angstrom. The position of the minimum is nearer to the C end, at R approximate to 3.7 A and - = 50 degrees. The influence of the selected geometry variations on the fundamental energy components, obtained from intermolecular perturbation theory, was also investigated. The separation of the interaction energy shows that the shape and location of these minima are primarily determined by the anisotropy of the exchange-penetration and dispersion components.