An approach to Hammond’s principle through Kullback–Leibler’s entropy

In this work, we used Kullback–Leibler’s entropy defined in terms of the occupation numbers, and it is grouped into the set of informational entropies, this entropy is considered a measure of the divergence between two probabilistic distributions, which permit to compare two chemical species. On the other hand, in the field of chemical reactions, since the middle of the 1950s Hammond’s postulate has been used to complement the description of chemical reactions, particularly the transition state structures, this postulate establishes that the transition state structure of a chemical reaction will be structurally similar to a structure with similar energy. In this work, we analyze seven chemical reactions, exothermic, thermoneutral, and endothermic, our results show that in some cases Hammond’s principle fails in its prediction, whereas Kullback-Leibler’s entropy does not.