Toward Quantitative Reaction Dynamics of O₃

The reaction dynamics of O(³P) + O₂(³Σ_g^-) collisions in the O₃(X¹A') electronic ground state is characterized on a high-level MRCI+Q/aug-cc-pVQZ potential energy surface (PES) represented as a reproducing kernel. For the atom exchange reactions involving the ¹⁶O and ¹⁸O isotopes with rates k₆^exch(T) and k₈^exch(T), a negative temperature dependence of k^exch(T), consistent with experiments was found. The absolute rates typically underestimate measured rates by ∼50%. For the ratio R(T) = k₈^exch(T)/k₆^exch(T), the measured T dependence was correctly captured with a maximum at ∼300 K. The differences between experiments and computations are primarily due to neglect of zero-point effects. For the dissociation reaction, the rate is lower by approximately 1 order of magnitude compared with experiments, which is a clear improvement over simulations using previous PESs. The present results support an electronic degeneracy factor of g_e^diss ∈ [1/27, 1] with a preference for values toward the lower end of the interval. Nonadiabatic effects are deemed to play only a minor role in the atom-exchange reaction.