Theoretical study on mechanism and rate constants for HCO+HNO₂ → HCHO+NO₂

The mechanism and kinetics for the reaction HCHO+NO₂ → HCHO+NO₂ have been studied theoretically. The transition state and the intrinsic reaction coordinate (IRC) curve of the reaction have been calculated by using the ab initio UHF/6-31G method. The corrected barrier at the UMP2/6-31G+ZPE level is 48.20 kJ mol^-1. By computing microcanonical probability fluxes at the transition state and the tunneling coefficient K(T) through the Eckart barrier, the calculated values of the thermal rate constants are in good agreement with the experimental results.