A semiclassical study of vibrational and rotational transition in He+H2 at suprathermal energies Original Research Article

Vibrational and rotational transition in suprathermal (> a few eV) He+H2 collisions is studied by using a semiclassical method in which one degree of freedom (i.e., relative radial motion) is described by classical mechanics and the others by quantum mechanics. The present study solves the semiclassical equation in a numerically accurate manner. That is, the vibration and orbital/molecular rotation are treated without employing any decoupled approximations. Also carried out are the semiclassical calculations using a centrifugal sudden (CS) and infinite order sudden (IOS) approximations. The comparison with the accurate semiclassical calculation shows that the CS approximation is always satisfactory, but the IOS approximation is not so good as one expected.