The reaction of CH_3 radicals with O(~3P) atoms was studied theoretically by means of the Gaussian-3 (G3) model calculation. The structures of the stationary points were optimized at the MP2 (full)/6- 31G~* and B3LYP/6-311 + + G~(**) level, and the intermediates and transition states were detected by the frequency analysis. At the same time, the energies yielded using the G3 model, and dynamics of the reaction were also discussed in this paper. The results of the theoretical study indicate that the CH_3 + O (~3P) reaction has four possible exothermic channels in which the main channel is IM1 → TS1 → CH_2O + H and the reaction forms CO by complete decomposition.

Key words: METHANE, FREE RADICAL, TRANSITION STATE, MOLECULAR ORBIT, AB INITIO CALCULATION, CONFIGURATION