Computational study on interaction energy changes during double proton transfer process

This paper reports the computational studies on the double proton transfer for: the formamide–formic acid, FM⋯FA and formamide–formamidine, FM⋯FI. Despite being accurate, total interaction energy does not provide any information about its partitioning into physically defined energy terms. The Symmetry-Adapted Perturbation Theory interaction-energy decomposition along the intrinsic reaction coordinates connecting the two equilibrium geometries via the transition state has been analyzed. No one term of the interaction energy was found to be solely responsible for the changes of interaction energy along the whole DPT path; however, the exchange and the induction terms have a major contribution.