A new rigid-rotor H2–CO potential energy surface from accurate a b i n i t i o calculations and rotationally inelastic scattering data

Abstract

We determined a new rigid-rotor potential energy surface for H2–CO by combining large basis set SCF calculations with damped long range dispersion coefficients. The damping function contains two parameters which were determined by comparison of experimental and calculated cross sections for oD2–CO scattering at E=87.2 meV. The dynamical calculations were performed within the coupled states approximation because neither a classical nor an energy sudden description of the CO rotation are accurate enough. It is found that the rotational rainbow structures of the energy transfer cross sections determine the relative anisotropy of the interaction potential, while the diffraction oscillations of the total differential cross section determine the absolute range of the effective spherically averaged potential. For a unique potential determination both sets of experimental data have to be fitted simultaneously.