An ab initio study of the intermolecular potential surfaces of HeCH 4 and NeCH 4

Abstract

The intermolecular potential surfaces for the Van der Waals complexes HeCH 4 and NeCH 4 are studied by ab initio theory using complete fourth-order Møller-Plesset perturbation theory (MP4) with an efficient basis set containing bond functions. For HeCH 4, the global minimum occurs at R = 3.4 A ̊ , θ = 180°, φ = 0° (in a Jacobi coordinate system) with a minimum energy D e = −26.2 cm −1. For NeCH 4, the global minimum occurs at R = 3.5 A ̊ , θ = 180°, φ = 0° with a minimum energy D e = −59.0 cm −1. Two saddle points were found for each of the systems. The potential energy surfaces are compared with the semiempirical surfaces and recent ab initio results on the same systems.