Spectral signatures of excess-proton waiting and transfer-path dynamics in aqueous hydrochloric acid solutions.

ABSTRACT: The theoretical basis for linking spectral signatures of hydrated excess protons with microscopic proton-transfer mechanisms has so far relied on normal-mode analysis. We introduce trajectory-decomposition techniques to analyze the excess-proton dynamics in ab initio molecular-dynamics simulations of aqueous hydrochloric-acid solutions beyond the normal-mode scenario. We show that the actual proton transfer between two water molecules involves for relatively large water-water separations crossing of a free-energy barrier and thus is not a normal mode, rather it is characterized by two non-vibrational time scales: Firstly, the broadly distributed waiting time for transfer to occur with a mean value of 200-300 fs, which leads to a broad and weak shoulder in the absorption spectrum around 100

SUBMITTER: Brunig FN 

PROVIDER: S-EPMC9304333 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature