Water exchange dynamics around H₃O⁺ and OH⁻ ions

Journal Article · Fri May 01 00:00:00 EDT 2015 · Chemical Physics Letters

DOI:https://doi.org/10.1016/j.cplett.2015.04.002· OSTI ID:1208762

Roy, Santanu ^[1]; Dang, Liem X. ^[1]

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1. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Proton transfer in water and other solvents is a complicated process and an active research area. Conformational changes of water hydrating a proton can have a significant influence on proton dynamics. A hydrated proton leads to H₃O⁺ that forms three hydrogen bonds with neighboring water molecules. In this letter, we report the first computer simulation of the dynamics of water exchanging between the first and second solvation shells of H₃O⁺. Employing different rate theories for chemical reactions such as the transition state theory, the Grote-Hynes theory, the reactive flux method, and the Impey-Madden-McDonald method, we calculate the solvent exchange rates from molecular dynamics simulations that account for explicit polarization effects. In addition, we also study water exchanges around OH⁻ and find that the corresponding time scale (~50 picoseconds [ps]) is much smaller than that for H₃O⁺ (~100 ps). Results from all the rate theories are computed and compared. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1208762
• Report Number(s): PNNL-SA-107652; KC0301020
• Journal Information: Chemical Physics Letters, Vol. 628, Issue C; ISSN 0009-2614
• Publisher: Elsevier
• Country of Publication: United States
• Language: English