A quantum symmetry preserving semiclassical method

Symmetry constraints are built into a semiclassical propagation scheme. It is then applied to treat H!Ne2 collisions at 30 K, where quantum selection rules restrict the final rotational states of symmetric Ne2 molecules to the even manifold. The cross sections for state-to-state transitions are calculated for symmetric and nonsymmetric isotopic compositions of Ne2 . All bound and long-lived quasibound !trapped behind the centrifugal barrier" states of Ne2 are considered. This semiclassical method captures symmetry effects and shows satisfactory agreement with the quantum results. © 2002 American Institute of Physics. #DOI: 10.1063/1.1513457$