Abstract: Reaction resonance or Feshbach resonance in polyatomic reaction is one of the most fascinating phenomena in chemical reaction dynamics. The HO+CH₄→H₂O+CH₃ reaction is one of the pivotal polyato-mic reactions concerned with both the experimental and theoretical scientists. Reaction probabilities and other dynamic properties of this system were calculated with quantum scattering theory method, but a simple QH(v)+HO(j)→Q+H₂O(m,n) reaction model was used, in which only three degrees of freedom and the rotating of OH were considered while making CH₃ as a pseudo atom. In this paper, by an ab initio method, partial potential energy surface(PPES) was constructed and all the 15 internal degrees-freedom were given. Feshbach resonance mechanism of this reaction can be obtained by the dynamic Eyring Lake on the PPES and the lifetime of the reactive resonance-state can be estimated using the gap of the vibrational energy levels of transient collision complex in the critical transition-state region. Above interesting dynamic properties would not be given by simple pseudo atomic reaction model.

Key words: HO+CH₄→H₂O+CH₃ reaction, Feshbach resonance, Partial potential energy surface, Transient collision complex, Vibrational dynamics