Ab initio based potential energy surface and kinetic studies of the H + HCF3 reaction

Abstract

In this study, the kinetics of hydrogen abstraction reaction H + HCF3 → H2 + CF3 are studied using both tunneling-corrected transition state and quasi-classical trajectory methods on a newly developed global potential energy surface (PES). The PES is constructed by fitting 31 968 ab initio points at the level of UCCSD(T)-F12a/aug-cc-pVTZ using the permutation invariant polynomial-neural network method. The thermal rate coefficients determined for both the forward and reverse reactions exhibit satisfactory agreement with the experimental observations, affirming the accuracy of the potential energy surface. In addition, an investigation into the kinetic isotope effects on the reverse reaction is carried out by substituting H2 with D2. These findings collectively serve as explicit evidence that quantum tunnelling plays a significant role, even under elevated temperature conditions.