A Theoretical Study On The Mechanism And Kinetics Of The Reaction Of O(~3P) With Propane

The reaction of C3H8 + O(3P) is investigated using the ab initio and dynamical methods. The electronic structure of C3H8 + O(3P) â†' C3H7+OH reaction are calculated by using a dual-level strategy, and more accurate energies are obtained. The geometry optimization is performed using the unrestricted second-order M(?)ller-Plesset perturbation method and the single-point energy are computed using the coupled-cluster singles and doubles augmented by a perturbative treatment of triple excitations method with the correlation-consistent quadruple-ε basis set of Dunning augmented with diffuse functions (aug-cc-pVTZ) basis set, the reaction barriers of three channels are obtained. The intrinsic reaction coordinate (IRC) calculations are carried out to confirm that the transition states connect the right minima. Our results indicate that the main reaction channel is C3H8+O(3P) â†' i-C3H7+OH. Based upon the ab initio data, the kinetic studies of the reaction are carried out. The thermal rate constants of three reaction channels are calculated using the variational transition state theory method with the temperature ranging from 298 K to 1000 K, and the branching ratios (kn/ki) of the reaction are also calculated in present work. These calculated results are in better agreement with experiments than those reported in previous theoretical studies. Furthermore, the isotope effects of the C3H8+O(3P) â†' i-C3H7+OH reaction are obtained and discussed. The present work reveals the reaction mechanism of hydrogen-abstraction from propane involving reaction channel competitions and is helpful for the understanding of propane combustion, and it can also provide an important reference for other hydrocarbon molecule combustion research.