A Quasiclassical Trajectory Study of the Cl + HCN → HCl + CN Reaction Dynamics. Microscopic Reaction Mechanism of the H(Cl) + HCN → H2(HCl) + CN Reactions

Abstract

The Cl + HCN → HCl + CN reaction dynamics has been studied using the quasiclassical trajectory method. The potential energy surface is taken from an accurate global surface for the HHCN system. Cl + HCN and H + HCN have very similar energetics, so the present calculation provides a test of whether the Cl + HCN dynamics is captured by a model in which the only difference is provided by the mass of the attacking atom. We find generally good agreement with experimental studies of the Cl + HCN reaction, including CN product rovibrational distributions and the relative rate coefficients for HCN initially in highly excited vibrational states. The results correctly describe the differences between Cl and H attack, so apparently the differences in the reactivity of these two reactions are a kinematic effect. A detailed analysis of the microscopic reaction mechanism of the H + HCN → H2 + CN and Cl + HCN → HCl + CN reactions is also provided. This shows that the H and Cl reactions are both dominated by direct dynam...