The subsequent minimum energy pathway is shown in Fig. . Here, the reaction pathway shows three pseudo-minima corresponding to the bases already part way slid into a Watson-Crick-like shape, the second, where the proton has transferred to the other base, and the third, the return of the proton back to the same base. The first minima have an energy difference of 0.621 eV compared to the ground state. Assuming this configuration is explored with a penalty in the form exp(-E/k B T ) gives a weighting of ∼ 3.18 × 10 -11 . The last two pseudo-minima indicates that, if we assume that the proton transfer is much faster than the rest of the atomic motion during the reaction, that a bifurcation of the reaction pathway is possible. In fact, after the first initial proton transfer, the rest of the atoms could rearrange, trapping the population in the middle well. This expected distribution of outcomes is consistent with the NMR experiments, which suggests the fast interchange between the Watson-Crick-like configurations but a slow initial formation due to the prohibitively high initial rearrangement cost to facilitate the transfer.