Quasi-classical calculations of elastic and rotationally and vibrationally inelastic differential cross sections for Li + + H 2

Abstract

The angular dependence of the differential elastic and inelastic cross sections for rotational quantum transitions was calculated for transitions Δ f=0,2,4,6 for Li + - H 2 and D 2 in the para and ortho states. These calculations and transition probabilities at E tt=0.6 and 1.2 eV were compared with converged close-coupling calculations on the same potential hypersurface. The overall agreement was between 7 and 100%. The largest errors (50-100%) were observed in the region of the rainbow, where quantum interference effects have a strong influence. At large angles the classical results agreed to within ⩽ 10%. Good agreement was also found between the predicted vibrational transition probabilities at large scattering angles and a recent time of flight experiment. Furthermore it was found that the location of the classical rainbow depends strongly on the anisotropy. Whereas the elastic and inelastic cross sections depend considerably on the isotopic mass and para-ortho species of the target the total differential cross section was nearly unaffected.