6533b82ffe1ef96bd1294f61

RESEARCH PRODUCT

Thermochemical analysis of the OH+C2H4→C2H4OH reaction using accurate theoretical methods

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Abstract The radical addition of hydroxyl radical to ethene has been investigated using ab initio methods and density functional theory. The structure and energetics of reactants, prereaction complex, transition state structure and radical product have been optimized and vibrational frequencies have been calculated at the HF, MP2, B88, and B3LYP level using 6-31G* and 6-311G** basis sets. The energetics of the reaction is characterized within the MP2, DFT, G2, CBS, and BAC approaches. The evolution of the barrier height and reaction enthalpy has been systematically investigated with respect to the methodological approach employed. The best agreement with experimental results for the barrier heights is found at the BAC-G2 and BAC-G2(MP2) levels. A reaction enthalpy of −28.4±1.2 kcal/mol is determined in clear accord with direct experimental data. The performance of the different theoretical methods and the reliability of DFT approach to describe this radical reaction is discussed.