QUANTUM SCATTERING STUDIES OF COLLISIONAL ENERGY-TRANSFER FROM HIGHLYEXCITED POLYATOMIC-MOLECULES - A BEND-STRETCH MODEL OF HE+CS2

We present the results of an accurate quantum scattering study of coll isional energy transfer in a bend-stretch model of the He + CS2 system , considering energies up to 45 kcal/mol. These results are generated using a coupled channel method, with vibrational eigenfunctions obtain ed from a discrete variable representation method. Detailed comparison s with the results of classical trajectory calculations are performed so as to assess classical/quantum correspondence for energy transfer m oments, and for the energy transfer probability distribution function. We find good agreement of the energy averaged first moments over a wi de range of molecular vibrational energies. The second moments, as wel l as (Delta E)(up) and (Delta E)(down) show less quantitative agreemen t. The quantum energy transfer distribution functions show considerabl e mode-specific behavior, but the overall envelope is approximately ex ponential at large \Delta E\ with a broad spike near \Delta E\ = 0. We analyze this behavior in terms of contributions from individual state -to-stale transition probabilities. The corresponding classical distri bution functions are very similar, showing better correspondence than was found for other models with smaller stale densities.