Ab initio rate coefficients for the reaction of OH and H2O2 under upper troposphere and lower stratosphere conditions

The reaction between hydrogen peroxide (H2O2) and hydroxyl radical (OH) plays an important role in the upper troposphere and lower stratosphere (UTLS). However, direct experimental studies are lacking for this UTLS regime for a temperature range of 190–250 K. In this work, mechanism and kinetics for the title reaction were studied using high-level theoretical methods to provide highly accurate rate coefficients for the UTLS regime. The reaction was found to proceed via a van der Waals (vdW) complex at low temperatures, but to undergo a direct H-abstraction via a well-skipping mechanism at higher temperature to yield products HO2 + H2O. The ab initio rate coefficients are pressure-independent under terrestrial atmospheric conditions (T = 180–350 K and P ≤ 1 atm) and agree well to within 20% with most experimental data available for T = 165–500 K.