A topological analysis of the proton transfer in H₅O⁺₂

Abstract

The proton transfer in the protonated water dimer (H5O+ 2) has been studied by following the evolution of bonds. This has been achieved by analysing ab initio density functional theory calculations using the bonding evolution theory. It is found that the breaking and reforming of covalent O—H+ bonds are not simultaneous. Therefore, the process is described as a succession of three topological structures. These results have been compared with a three-state valence bond model and found to be in good agreement. The topological approach provides reliable results for further applications to the analysis of fully ab initio molecular dynamics simulations or to the parametrization of simple empirical valence bond models to be included in molecular dynamics force fields.