Resonance and reaction

We examine two thermal reaction rates which can be defined for a one-dimensional model of a reaction dominated by a transient resonance. One of the rates corresponds to thermally equilibrated reactants in the region preceding the symmetrical double barrier potential supporting the intermediate complex. The other rate corresponds to pre-reaction thermal equilibration extending over the intermediate species. One rate is found to be twice the other. Numerical and analytical arguments are given to reach this conclusion. This discussion leads to a restrictive condition in the application of a formula given previously (R. Lefebvre and N. Moiseyev, J. Chem. Phys., 93 (1990) 7173) to relate the rate in the tunnelling regime to the set of artificial resonances produced by box quantization.