Quantum dynamics of SN2 reactions on CCSD(T) potential energy surfaces: Cl−+CH3Cl and Cl−+CH3Br

Quantum mechanical cross-sections for the collinear SN2 reactions Cl−+CH3Cl′ → ClCH3+Cl′− and Cl−+CH3Br → ClCH3+Br− have been calculated within the time-independent hyperspherical coordinate approach employing two-dimensional CCSD(T) potential energy surfaces. Compared to the results obtained from the potentials of Hase and co-workers, the recent cross-sections show several different features. However, the cross-sections calculated using the CCSD(T) potential energy surface for Cl−+CH3Br do not explain the experimentally observed independence of the rate constant on initial CH3Br temperature.