Theoretical study of stereodynamics for the reactions Cl+H2/HD/D2

Studies on the dynamical stereochemistry of the Cl+H-2 reaction and its isotopic variants, especially the isotope effect on the product polarization, have been performed at a collision energy of 6.0 kcal/mol on two potential energy surfaces, i.e., G3 surface [T. C. Allison , J. Phys. Chem. 100, 13575 (1996)] and BW2 surface [W. Bian and H.-J. Werner, J. Chem. Phys. 112, 220 (2000)]. Quantum mechanical and quasiclassical trajectories calculations of the polarization-dependent differential cross sections for the Cl+H-2 reaction have been carried out on the BW2 potential energy surface, and the results indicate that the quasiclassical approximation in general does as good as exact quantum mechanics. Calculations also show that the rotational alignment of the HCl product obtained on the BW2 surface for Cl+H-2 reaction is stronger than that calculated on the G3 surface, which implies that the effect of van der Waals force on product polarization is quite weak. The distributions of P(theta(r)) and P(phi(r)) derived from the Cl+H-2 and its isotopic reactions indicate that the isotope effect on the product polarization calculated on the G3 potential energy surface is distinct, whereas the isotope effect on the product polarization computed on the BW2 surface is indistinct. (C) 2003 American Institute of Physics.