Stereodynamics and rovibrational effect for H+CH4(v,j,K,n)→H2+CH3 reaction

In this work, we employ the semirigid vibrating rotor target (SVRT) model to study the influence of rotational and vibrational excitation of the reagent on reactivity for the benchmark reaction H+CH4(v,j,K,n). The excitation of the pseudo H-CH3 stretching vibration of the SVRT model gives significant enhancement of reaction probability, consistent with the later position of the reaction barrier on the potential energy surface. The vibrationally thermal-averaged rate constant is much larger than the rate constant of the ground vibrational state. Detailed study of the influence of initial rotational states on reaction probability shows strong steric effect. The reaction probability is directly correlated with the angular distribution of the initial wave function determined by different angular momentum relationships among three vectors j, R, and r. The steric effect of polyatomic reactions, treated by the SVRT model, is more complex and richer than theoretical calculations involving linear molecular models. (C) 2002 American Institute of Physics.