A new potential energy surface for He–H2CO

The intermolecular potential energy surface (PES) for He–H2CO has been calculated using the CCSD(T) method. A basis set extrapolation procedure was employed to estimate the complete basis set limit. For comparison, analogous calculations were also carried out on He–CO. Three minima were identified for He–H2CO, all arising from planar structures of the complex. The global minimum corresponds to an approximately T-shaped arrangement of the helium atom with respect to the CO bond. A well depth of 59.5 cm−1 was obtained for the global minimum, more than double that reported in an earlier ab initio study of He–H2CO. The implications of this new PES for spectroscopic studies of He–H2CO and for understanding He + H2CO scattering processes is discussed.