ROTATIONALLY INELASTIC-COLLISIONS OF LI2(A1-SIGMA-U+) WITH NE - FULLY ABINITIO CROSS-SECTIONS AND COMPARISON WITH EXPERIMENT

The potential energy surface (PES) for the interaction of Li2(A 1-SIGMA-u+) with Ne has been computed using highly correlated multiconfiguration-reference configuration expansions (MRCI) and a large basis set. From the calculated points an analytical fit of the potential was obtained. Particular care was used to ensure a smooth fit to the angular dependence of this highly anisotropic potential. This PES has been used in exact close-coupling (CC) quantum scattering calculations of cross sections for rotationally inelastic collisions. The dependence of the calculated cross sections on velocity, as well as on the initial and final states, is found to be in excellent agreement with the measurements of Smith, Scott, and Pritchard [J. Chem. Phys. 80, 4841 (1984);81, 1229 (1984)]. For comparison, cross sections were also computed within the coupled-states (CS) approximation. At low collision energies the CS results deviate significantly from both the exact CC results and the experimental data.