ENERGY-DEPENDENCE OF THE REACTION CROSS-SECTION FOR THE F+H2(UPSILON=0,J=0,1,2)-]HF(UPSILON')+H REACTION FROM QUASI-CLASSICAL TRAJECTORY CALCULATIONS

The collision energy dependence of the reaction cross section (i.e. the translational excitation function) for the F + H2(upsilon = 0, j = 0, 1, 2) --> HF + H system has been obtained from quasiclassical trajectory calculations on two potential energy surfaces: an empirical one by Takayanagi and Sato (Chem. Phys. Letters 144 (1988) 191, based on the London-Eyring-Polanyi-Sato (LEPS) functionality and the last published semiempirical surface by Mielke et al. (Chem. Phys. Letters 213 (1993) 10). In contrast with the relatively featureless excitation functions sigma(R)(E(T), j) obtained on the potential surface of Mielke et al., the ones calculated on the LEPS surface exhibit a richness of features surprising at a first sight for a classical calculation on an empirical surface. This different behaviour is discussed in terms of the distinct topology of both surfaces. A comparison of the experimental rate constants with the ones calculated from the excitation functions obtained on the LEPS surface indicates that its barrier height is too low. Differential cross sections for the F + n-H-2 reaction are calculated on both surfaces, showing a reasonable agreement with experiment.