Calculation of the rate constant for the reaction of atomic hydrogen with molecular oxygen to form the free radical HO2

A temperature dependent rate constant for the H+O2+M→HO2+M* recombination reaction has been calculated using classical dynamics and the kinetic theory of gases. A complete potential energy surface for the interaction of H with O2 has been calculated previously. This potential energy surface was used in conjunction with classical dynamics to calculate the equilibrium constant for the production of HO2* from the reaction H+O2?HO2* where HO2* indicates the HO2 molecule with excess internal energy. The kinetic theory of gases is used to determine the quenching rate, HO2*+M→HO2+M*, by a third body collision. A collision efficiency factor, dependent on the amount of excess energy in HO2*, is included in the calculation. The results indicate that the lifetime of the HO2* species is not the dominant factor in determining the temperature dependence of the rate constant. Rather the efficiency of the third-body in removing the excess energy determines the temperature dependence of the rate constant. Argon is the representative third body used in these calculations.