Entropic effects on the dynamical bottleneck location and tunneling contributions for C2H4 + H -> C2H5: variable scaling of external correlation energy for association reactions

A study based on variational transition state theory was conducted on the temperature dependence of the dynamical bottleneck location for the prototype olefin addition process H + C2H4. A method called variable scaling of external correlation which uses a scale factor was developed. The findings indicate that tunneling effects are quantitatively responsible for the curvature of the Arrhenius plots.