Ab initio potential energy surfaces of He-CO2 and Ne-CO2 van der Waals complexes

We have calculated ab initio the ground-state potential energy surfaces of Ne-CO2 and He-CO2 van der Waals complexes by using the fourth-order Moller-Plesset perturbation theory with a large basis set containing bond functions. The rigid molecule approximation has been used for CO2. Both complexes have the lowest energy at the T-shaped configuration. In addition, a shallow minimum is found for the linear configuration, with a small barrier connecting the two minima on the potential energy surface, whose height is larger for the lighter noble-gas atom. The implications of these potentials for the wetting behavior of adsorbed films are discussed.