Revisiting the reaction energetics of the CH3O˙ + O2 (3Σ−) reaction: the crucial role of post-CCSD(T) corrections

Abstract

The CH₃O˙ + O₂ reaction has been studied by means of high level ab initio calculations to predict the reaction energy and barrier height with chemical accuracy. We have employed post-CCSD(T) corrections in terms of partial quadratic excitations at the coupled cluster level, along with relativistic, core, spin–orbit and diagonal Born–Oppenheimer corrections, to estimate the barrier height and energetics for the title reaction. After including all the corrections, the reaction energy and barrier height were found to be −26.86 and 2.59 kcal mol⁻¹, respectively, which is in good agreement with the corresponding experimentally derived values. Using this information, we have also calculated the rate constants for the title reaction employing transition state theory (TST) in conjunction with zero curvature tunneling (ZCT) within a temperature range of 250 to 900 K.