Ab initio potential energy surface for the reaction of O(3P) with CH2F

The potential energy surface (PES) for the reaction of an oxygen atom with a fluorinated methyl radical has been studied using the G2MP2 level of theory. The calculations reveal an association-elimination mechanism. The addition reaction of O(P-3) to CH2F produces an energy-rich intermediate OCH2F* which subsequently decomposes irreversibly. Five production channels of OCH2F* are found: H + CHFO, HF + HCO, CHFOH, F + CH2O and H-2 + FCO. CHFOH can decompose through six production channels: H + CHFO, HF + HCO, H + HCOF, H-2 + FCO, F + HCOH and OH + CHF. Based on the present ab initio PES, the kinetic characteristics of the O(P-3) + CH2F reaction are estimated. The energy-specific rate constants for the unimolecular decomposition of OCH,F are calculated by RRKM theory. H + CHFO are predicted to be the major products. (C) 1999 Elsevier Science B.V. All rights reserved.