Inelastic collisions of molecular hydrogen: A comparison of results from quantum and classical mechanics

Full-dimensional quantum and classical calculations have been carried out for inelastic (nonreactive) energy transfer in H-2+H-2 on the ab initio potential energy surface of Boothroyd [J. Chem. Phys. 116, 666 (2002)]. State-to-state cross sections are determined and compared for transitions from H-2(0,j(ab))+H-2(1,j(cd)). While there is excellent agreement for transitions involving small Deltaj, for larger Deltaj and for vibrational relaxation, significant differences are observed which exhibit no systematic trends. Reasons for this disagreement are discussed. (C) 2004 American Institute of Physics.