Ab initio basis set study of the CO⋯He van der Waals interaction

Abstract

The ab initio potential energy surface for the weakly bound van der Waals CO⋯He has been performed in the framework of the supermolecule approach, using fourth order Møller–Plesset perturbation theory with different basis sets, constructed to give accurate values for the electric moments and polarizabilities, supplemented by bond functions placed at the midpoint along the line joining He with the center of mass of CO. All atom-centered basis sets explored in the present study predict single-minimum near collinear C–O⋯He optimum structures. Near T-shaped optimum structures are predicted when these basis sets are augmented with a set of bond functions located in the middle of the van der Waals bond, in agreement with recent experimental and ab initio potentials.