Isotope effects on the dynamics properties and reaction mechanism in the Cl(2P) + NH3 reaction: a QCT and QM study

Isotope effects on dynamics properties and reaction mechanism in the title reaction, which evolve through deep wells in the entry and exit channels, were analysed using both quasi-classical trajectory and reduced dimensional quantum mechanical calculations, for collision energies in the range 3.0-10.0 kcal mol(-1), on an analytical potential energy surface (PES-2010) recently developed by our group. The analysis of different dynamics properties (reaction probability, product energy partitioning, and product rovibrational distributions) shows the reaction behaviour of the two reactions, Cl + NH3 and Cl + ND3, to be similar: direct mechanism, with a small percentage of indirect mechanisms, that is, trapping complex mediated. We find that the only dynamics property dependent on the isotope effect is the product scattering distribution. In particular, while the perdeuterated reaction favours backward scattering, the perprotio analogue favours forward scattering. This behaviour is related to the smaller maximum impact parameter for the perdeuterated reaction.