Abstract: The reaction mechanisms and molecular dynamics of the multi-channel reaction H＋CH2CO which might occur through four channels depending on the different initial reaction positions of the reactants CH2CO are detailedly studied. All the calculations are performed at the UQCISD/6-311G (d,p) and G2 theory level. Every transition state is confirmed by the numbers of virtual frequency and the intrinsic reaction coordinate (IRC) paths. The computational results suggest that the reaction channel of forming CH3＋CO through an intermediate is the dominant one. This channel is an exothermic reaction whose enthalpy changes are －146.07 kJ•mol－1 and the calculated potential barrier of the rate-determining step is 55.09 kJ•mol－1. The obtained reaction potential profile can qualitatively explain the experimental coexistence phenomena of the primary products and the other minor products.

Key words: Ketene, Atomic hydrogen, Ab initio study, G2 theory