Kinetic study of methyl radical oxidation with molecular oxygen

摘要

The reaction of methyl radical with molecular oxygen is studied over broad temperature and pressure ranges using high level ab initio electronic structure theory and transition state theory. The barrierless channels are treated with variable reaction coordinate transition state theory (VRC-TST). The interactions energies in these VRC-TST calculations are calculated directly using multireference Rayleigh Schrodinger second order perturbation theory (CASPT2) with an augmented correlation consistent polarized valence double-zeta basis set (aug-cc-pVDZ). Potential energy corrections due to geometry relaxation and complete basis set extrapolation are included in the reactive flux calculation. The rate constants for the association reaction (CH_3 ＋ O_2 →CH_3O_2) for different bath gas colliders (Ar, He, N_2 and CO_2) and product formation channels (CH_3 + O_2 →CH_2O＋ OH and CH_3 + O_2 → CH_3O＋ O) are calculated and compared with the experimental data.