Analytical potential energy surface for the CH4+Cl->CH3+ClH reaction: Application of the variational transition state theory and analysis of the kinetic isotope effects

We present a potential energy surface for the CH4+Cl-->CH3+Cl reaction, based on the analytical function J1 for the analog CH4+H-->CH3+H-2 reaction by Joseph et al. To calibrate the new surface we chose the reactant and product experimental properties as reference data. The forward and reverse rate constants were calculated using variational transition state theory with large curvature transmission coefficients over a wide temperature range, 200-1000 K. The variational effects were concluded to be small for this reaction, and good agreement with experimental rate constants was found in both forward and reverse reactions. The kinetic isotope effects (KIEs) at different temperatures for the forward and reverse reactions were also analyzed showing always a ''normal'' behavior. The factor analysis of the KIEs in the forward reactions indicated high vibrational and tunneling contributions at low temperatures. (C) 1996 American Institute of Physics.