A close coupling calculation for inelastic collisions of protons on H2 molecules at 3.7 eV

An ab initio computed potential surface for the H3+ system at various geometries is expanded in Legendre polynomials and the ensuing radial coefficients are employed to yield the S-matrix elements from the close coupling expansion of the scattering equations, at the collision energy of recently performed molecular beam experiments. The rotationally inelastic cross sections are obtained for an energy corrected, rigid rotor H2 target and the influence of increasing the basis set size is discussed. The dominant contribution of the charge--quadrupole interaction to the computed observables is examined and an interesting effect is observed on the impact parameter dependence of the 0→2 excitation cross section. All these features are explained in terms of the special nature of the proton interaction with the molecular system and of the dynamics that stem from it