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. (C) 2003 Elsevier Science B.V. All rights reserved.