(\ Multichannel RRKM-SSA and CVT Rate Constant Calculations for the Reaction of H2S(1A1) with HO2(2A

An understanding of the oxidation of sulfur containing species such as H2S, is important to describing both the oxidation of sulfur-containing fuels and the behavior of sulfur pollutants in the atmosphere. The kinetics and mechanism of the reaction of hydrogen sulfide (H2S(1A1)) with hydroperoxyl radical (HO2(2Aʺ)) on the lowest doublet potential energy surface have been theoretically studied. The potential energy surface for each possible pathway has been investigated by employing CBS, DFT, and CCSD(T) methods. Three different pathways are suggested to be possible for the title reaction. The most probable channel consists of one hydrogen-bonded complex (vdw1) and two energized intermediates. Multichannel RRKM-SSA method1 and direct dynamics canonical variational transition-state theory (CVT)2 calculations have been carried out to compute the temperature dependence of the individual rate constants for different channels and also the overall rate constant for the consumption of the reactants. We have shown that the major products of the title reaction are H2O2 and SH while at high temperatures, formation of other products such as H2O, HOS, HSOH and OH also become important.