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.