Eq. 26 allows for attribution of the vibrational energy to bonds and contacts in the reacting system. This has been envisaged by calculating the K parameter (eq. 28 and 30) traced along the IRC reaction path and the principal results have been presented in Fig. . The vibrational energy contribution has been dominated by the bonds undergoing changes N1-H4 and O3-H4, (Fig. ). However, the method has been sufficiently sensitive as to discover even the minute variations in other bonds and contacts playing a role in this reaction (Fig. ). While no results for this same reaction have been available in order to judge the efficiency of the present method, the general feature of the characteristics in Fig. may be compared to the curvature diagrams reported by Kraka & Cremer for the similar proton transfer reaction: S⎯C(H)OH → HSC(H)⎯O. The scalar curvature characteristics for bonds reported in this work are dominated by the O-H bond cleavage at the reaction onset (-1), and by the S-H bond formation peak in the reaction decay (1). The analogy to the shape, location and role of the N1-H4 and O3-H4 curves in Fig. is striking, and calls for formal analysis of the relevance between the two methodologies for monitoring reaction progress.