Ab Initio/Density Functional Theory and Multichannel RRKM Study for the ClO + CH2O Reaction

The potential energy surface for the CH2O + ClO reaction was calculated at the QCISD(T)/6-311G(2d,2p)//B3LYP/6-311G(d,p) level of theory. The rate constants for the lower barrier reaction channels producing HOCl + HCO, H atom, OCH2OCl, cis-HC(O)OCl and trans-HC(O)OCl have been calculated by TST and multichannel RRKM theory. Over the temperature range of 200−2000 K, the overall rate constants were k(200−2000K) = 1.19 × 10-13T0.79 exp(−3000.00/T). At 250 K, the calculated overall rate constant was 5.80 × 10-17 cm3 molecule-1 s-1, which was in good agreement with the experimental upper limit data. The calculated results demonstrated that the formation of HOCl + HCO was the dominant reaction channel and was exothermic by 9.7 kcal/mol with a barrier of 5.0 kcal/mol. When it retrograded to the reactants CH2O + ClO, an energy barrier of 14.7 kcal/mol is required. Furthermore, when HOCl decomposed into H + ClO, the energy required was 93.3 kcal/mol. These results suggest that the decomposition in both the forward...