Full-dimensional quantum mechanical calculation of the rate constant for the H2+OH→H2O+H reaction

The cumulative reaction probability (CRP) (the Boltzmann average of which is the thermal rate constant) has been calculated for the reaction H2+OH↔H2O+H in its full (six) dimensionality for total angular momentum J=0. The calculation, which should be the (numerically) exact result for the assumed potential energy surface, was carried out by a direct procedure that avoids having to solve the complete state-to-state reactive scattering problem. Higher angular momenta (J≳0) were taken into account approximately to obtain the thermal rate constant k(T) over the range 300<T<700 K; the result is significantly larger than the experimental values (a factor of ∼4 at 300 K), indicating that a more accurate potential energy surface is needed in order to provide a quantitative description of this reaction.