Special pair dance and partner selection: Elementary steps in proton transport in liquid water

Orner Markovitch, Hanning Chen, Sergei Izvekov, Francesco Paesani, Gregory A. Voth, Noam Agmon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

292 Scopus citations

Abstract

Conditional and time-dependent radial distribution functions reveal the details of the water structure surrounding the hydronium during the proton mobility process. Using this methodology for classical multistate empirical valence bond (MS-EVB) and ab initio molecular dynamics trajectories, as well as quantal MS-EVB trajectories, we supply statistical proof that proton hops in liquid water occur by a transition from the H3O+[3H 2O] Eigen-complex, via the H5O2+ Zundel-complex, to a H3O+[3H2O] centered on a neighboring water molecule. In the "resting period" before a transition, there is a distorted hydronium with one of its water ligands at a shorter distance and another at a longer distance than average. The identity of this "special partner" interchanges rapidly within the three first-shell water ligands. This is coupled to cleavage of an acceptor-type hydrogen bond. Just before the transition, a partner is selected by an additional translation of the H3O+ moiety in its direction, possibly enabled by loosening of donor-type hydrogen bonds on the opposite side. We monitor the transition in real time, showing how the average structure is converted to a distorted H5O2+ cation constituting the transitional complex for proton hopping between water molecules.

Original languageEnglish
Pages (from-to)9456-9466
Number of pages11
JournalJournal of Physical Chemistry B
Volume112
Issue number31
DOIs
StatePublished - 7 Aug 2008

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