Xie Zhen, Bowman Joel M, Zhang Xiubin
Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA.
J Chem Phys. 2006 Oct 7;125(13):133120. doi: 10.1063/1.2238871.
Detailed quasiclassical trajectory calculations of the reaction H+CH4(nu3 = 0,1)-->CH3 + H2 using a slightly updated version of a recent ab initio-based CH5 potential energy surface [X. Zhang et al., J. Chem. Phys. 124, 021104 (2006)] are reported. The reaction cross sections are calculated at initial relative translational energies of 1.52, 1.85, and 2.20 eV in order to make direct comparison with experiment. The relative reaction cross section enhancement ratio due to the excitation of the C-H antisymmetric stretch varies from 2.2 to 3.0 over this energy range, in good agreement with the experimental result of 3.0 +/- 1.5 [J. P. Camden et al., J. Chem. Phys. 123, 134301 (2005)]. The laboratory-frame speed and center-of-mass angular distributions of CH3 are calculated as are the vibrational and rotational distributions of H2 and CH3. We confirm that this reaction occurs with a combination of stripping and rebound mechanisms by presenting the impact parameter dependence of these distributions and also by direct examination of trajectories.
报道了使用基于最近从头算的CH5势能面的稍微更新版本[X. Zhang等人，《化学物理杂志》124, 021104 (2006)]对反应H + CH4(ν3 = 0,1)→CH3 + H2进行的详细准经典轨迹计算。为了与实验进行直接比较，在初始相对平动能量为1.52、1.85和2.20 eV下计算了反应截面。在该能量范围内，由于C - H反对称伸缩振动激发导致的相对反应截面增强比在2.2至3.0之间变化，与3.0±1.5的实验结果[J. P. Camden等人，《化学物理杂志》123, 134301 (2005)]良好吻合。计算了CH3在实验室坐标系中的速度和质心角分布，以及H2和CH3的振动和转动分布。通过给出这些分布的碰撞参数依赖性以及直接检查轨迹，我们证实该反应是通过剥离和反弹机制的组合发生的。
