Theoretical study on the mechanism ch4+c2h2+ reaction: mode- enhancement effect
J. Chem. Phys., 109 (1):
56--62 (1998)Abstract
High level nb initio calculations have been performed to investigate the mechanism of the ion-molecule reaction of CH4 + C2H2+. Except for some subtle differences, the profile for the H-abstraction channel obtained here at the G2M//B3PW91/6-311 G(d,p) level is very similar to that found in a previous study at the G2//MP2/6-31G(d) level. For the complex formation channel, however, a different transition slate has been located; the geometry and energetics of which are more consistent with experimental findings. Calculations of a few direct trajectories have been carried out to investigate the possible reason for the significant mode enhancement observed experimentally for the H-abstraction channel. Although none of them is reactive, a trajectory with an asymmetric C2H bend excitation exhibits a clear signature for being more reactive than those without vibrational excitation or with a symmetric bend excitation. (C) 1998 American Institute of Physics. S0021-9606(98)30125-7.