  Quantum-mechanical close-coupling calculations for state-to-state cross
sections and thermal rates are reported for H2+H2 collisions. Two recently
developed potential energy surfaces (PES) for the H2-H2 system are applied,
namely, the global potential surface from the work of A.I. Boothroyd, P.G.
Martin, W.J. Keogh, M.J. Peterson, J. Chem. Phys., 116 (2002) 666, and a
restricted, model surface from the works of P. Diep, J.K. Johnson, J. Chem.
Phys., 113 (2000) 3480; ibid. 112, 4465. The low temperature limit is
investigated. We found significant differences in cross sections and
corresponding thermal rates calculated with these two PESs.
