Theoretical Study on the Reaction Mechanism of CH3CH2+O(3P)

The reaction for CH3CH2+O(3P) was studied by ab initio method. The geometries of the reactants， intermediates， transition states and products were optimized at MP2/6-311+G(d,p) level. The corresponding vibration frequencies were calculated at the same level. The single-point calculations for all the stationary points were carried out at the QCISD(T)/6-311+G(d,p) level using the MP2/6-311+G(d,p) optimized geometries. The results of the theoretical study indicate that the major products are the CH2O＋CH3， CH3CHO+H and CH2CH2+OH in the reaction. For the products CH2O＋CH3 and CH3CHO+H， the major production channels are A1: (R)→IM1→TS3→(A) and B1: (R)→IM1→TS4→(B)， respectively. The majority of the products CH2CH2+OH are formed via the direct abstraction channels C1 and C2: (R)→TS1(TS2)→(C). In addition, the results suggest that the barrier heights to form the CO reaction channels are very high, so the CO is not a major product in the reaction.