Theoretical and kinetic study of the reaction of C2H3 + HO2 on the C2H3O2H potential energy surface

Abstract

The potential energy surface (PES) for reaction of C₂H₃ + HO₂ was examined by using high-level quantum chemical methods. Conventional transition state theory (TST) was used to determine the rates where the reaction has a tight transition state; variable reaction coordinate transition-state theory (VRC-TST) was used for rate constant calculations corresponding to the barrierless reactions. And Rice–Ramsberger–Kassel–Marcus/Master-Equation (RRKM/ME) theory was used to calculate the pressure-dependent rate constants of these channels. The major product channel of the reaction C₂H₃ + HO₂ is the formation of C₂H₃O₂H via a highly vibrationally excited product. Thermochemical properties of the species involved in the reactions were determined using the QCISD(T)/CBS//M062X/6-311++G(d,p) method and enthalpies of formation of species were compared with literature values. The calculated rate constants are in good agreement with limited data from the literature and are given in modified Arrhenius equation form, which are useful in combustion modeling of hydrocarbons. Finally, in order to investigate the effect of the calculated parameters on ignition delay, they were used to simulate ignition delay with the current mainstream mechanism. It is shown that these parameters have improved the mechanism and that the simulation results for ethylene ignition in a shock tube are similar to the observed values.