Theoretical study on kinetics of the H2CO + O2 → HCO + HO2 reaction

A direct ab initio dynamics study on the O2 + H2CO → HO2 + HCO reaction has been carried out from first principles using canonical variational transition state theory incorporating corrections from small curvature tunneling and hindered rotation treatments. Rate constants were calculated using the geometries, gradient and Hessian obtained at the BH&HLYP/cc-pVDZ level with the energy correction at the CCSD(T)/aug-cc-pVTZ//BH&HLYP/cc-pVDZ level. The rate constant expression is obtained as k(t)=2.95×10-21×T3.152×exp-18352T (cm3 molecule−1 s−1) for the temperature range 300-3000 K. The result shows an excellent agreement with available scattered experimental data over this temperature range and thus the expression can be used confidently for the whole range.