Dynamics of the CH3 + OH reaction

We study dynamics of the CH₃ + OH reaction over the temperature range of 300–2500 K using a quasiclassical method for the potential energy composed of explicit forms of short‐range and long‐range interactions. The explicit potential energy used in the study gives minimum energy paths on potential energy surfaces showing barrier heights, channel energies, and van der Waals well, which are consistent with ab initio calculations. Approximately, 20% of CH₃ + OH collisions undergo OH dissociation in a direct‐mode mechanism on a subpicosecond scale (<50 fs) with the rate coefficient as high as ～10^?10 cm³ molecule^?1 s^?1. Less than 10% leads to the formation of excited intermediates CH₃OH? with excess vibrational energies in CO and OH bonds. CH₃OH? stabilizes to CH₃OH, redissociates back to reactants, or forms one of various products after intramolecular energy redistribution via bond dissociation and formation on the time scale of 50–200 fs. The principal product is ¹CH₂ (k being ～10^?11), whereas ks for CH₂OH, CH₂O, and CH₃O are ～10^?12. The minor products are HCOH and CH₄ (k～10^?13). The total rate coefficient for CH₃ + OH → CH₃OH? → products is ～10^?11 and is weakly dependent on temperature. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 455–466, 2011