Reduced-dimensionality quantum reactive scattering calculations of the C(3P)Â +Â C2H2 reaction on a new potential energy surface

The reaction of the ground-state carbon atom with acetylene has been theoretically studied by a reduced dimensionality method, where three degrees of freedom were taken into account in the quantum dynamics calculations. A three-dimensional potential energy surface has been developed on the basis of the B3LYP/6-31G(d,p) level electronic structure calculations. The total reactive cross sections have been calculated by the time-independent generalized R-matrix method with the use of the negative imaginary potential. The reactive cross sections obtained in the energy range between 0.1 and 20 kJ/mol show a qualitative trend that is consistent with the barrierless reaction but the energy dependence was found to be much weaker than the experimental results. It has also been found that excitation of the initial rotation does not affect the reactivity but excitation of the CC stretch significantly decreases the reaction cross section.