Impact of Post-CCSD(T) Corrections on Reaction Energetics and Rate Constants of the OH^• + HCl Reaction

High level ab initio calculations have been performed to predict the reaction energy and barrier height for the OH• + HCl reaction. After including the effect of full quadratic excitations at the coupled cluster level, in addition to core, relativistic, spin–orbit, and diagonal Born–Oppenheimer corrections, we found the values of reaction energy and barrier height to be −15.29 and +2.38 kcal mol–1, respectively. Employing this reaction energy and barrier height, we used variational transition state theory in conjunction with small curvature tunneling to calculate the rate constants within a temperature range from 138 to 1000 K. The calculated rate constants were found to be in good agreement with available experimental results throughout the whole temperature range