Temperature Dependence of the Reaction HCl + OH → Cl + H2O between 140 and 1100 K

Abstract

Temperature dependence of the molecule‐radical reaction HCl + OH → Cl + H2O at temperatures between 140 and 1100 K is studied using a quasiclassical trajectory method. Potential energy surfaces are formulated using pair‐wise additive two‐body, nonadditive three‐body, and four‐body analytic forms and long‐range interactions. At temperatures above 300 K, the reaction occurs by direct collisions and the calculated rate constant fits the Arrhenius equation kdir = 4.85 × 10−12 exp.(−631 ± 10/T) cm3/molecule/s. At temperatures below 300 K, the reaction is driven by an attractive potential and occurs through the formation of a ClH…OH collision complex, which is sufficiently long‐lived to enhance quantum mechanical tunneling of the H atoms. The sum of the direct and complex‐mode reaction rates effectively describes the reaction occurring at temperatures in the 140–1100 K temperature range.