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Title: An analysis of hydrated proton diffusion in ab initio molecular dynamics

Abstract

A detailed understanding of the inherently multiscale proton transport process raises a number of scientifically challenging questions. For example, there remain many (partially addressed) questions on the molecular mechanism for long-range proton migration and the potential for the formation of long-lived traps giving rise to burst-and-rest proton dynamics. Using results from a sizeable collection of ab initio molecular dynamics (AIMD) simulations (totaling ∼2.7 ns) with various density functional approximations (Becke-Lee-Yang-Parr (BLYP), BLYP–D3, Hamprecht-Cohen-Tozer-Handy, B3LYP) and temperatures (300–330 K), equilibrium and dynamical properties of one excess proton and 128 water molecules are studied. Two features in particular (concerted hops and weak hydrogen-bond donors) are investigated to identify modes in the system that are strongly correlated with the onset of periods of burst-and-rest dynamics. The question of concerted hops seeks to identify those time scales over which long-range proton transport can be classified as a series of sequential water hopping events or as a near-simultaneous concerted process along compressed water wires. The coupling of the observed burst-and-rest dynamics with motions of a fourth neighboring water molecule (a weak hydrogen-bond donor) solvating the protonated water molecule is also investigated. The presence (absence) of hydrogen bonds involving this fourth water molecule before and aftermore » successful proton hopping events is found to be strongly correlated with periods of burst (rest) dynamics (and consistent with pre-solvation concepts). By analyzing several realizations of the AIMD trajectories on the 100-ps time scale, convergence of statistics can be assessed. For instance, it was observed that the probability for a fourth water molecule to approach the hydronium, if not already proximal at the beginning of the lifetime of the hydronium, is very low, indicative of the formation of stable void regions. Furthermore, the correlations of the neighboring water atoms are identified as the fourth water approaches the hydronium. Finally, the temperature effects on structural and dynamical properties are studied.« less

Authors:
;  [1]
  1. Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
Publication Date:
OSTI Identifier:
22415450
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 142; Journal Issue: 1; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; APPROXIMATIONS; ATOMS; COMPUTERIZED SIMULATION; CORRELATIONS; COUPLING; DENSITY FUNCTIONAL METHOD; DIFFUSION; HYDROGEN; LIFETIME; MOLECULAR DYNAMICS METHOD; MOLECULES; POTENTIALS; PROBABILITY; PROTON TRANSPORT; PROTONS; SOLVATION; STATISTICS; TEMPERATURE DEPENDENCE; TRAPS; WATER

Citation Formats

Tse, Ying-Lung Steve, Voth, Gregory A., E-mail: gavoth@uchicago.edu, and Knight, Chris. An analysis of hydrated proton diffusion in ab initio molecular dynamics. United States: N. p., 2015. Web. doi:10.1063/1.4905077.
Tse, Ying-Lung Steve, Voth, Gregory A., E-mail: gavoth@uchicago.edu, & Knight, Chris. An analysis of hydrated proton diffusion in ab initio molecular dynamics. United States. https://doi.org/10.1063/1.4905077
Tse, Ying-Lung Steve, Voth, Gregory A., E-mail: gavoth@uchicago.edu, and Knight, Chris. 2015. "An analysis of hydrated proton diffusion in ab initio molecular dynamics". United States. https://doi.org/10.1063/1.4905077.
@article{osti_22415450,
title = {An analysis of hydrated proton diffusion in ab initio molecular dynamics},
author = {Tse, Ying-Lung Steve and Voth, Gregory A., E-mail: gavoth@uchicago.edu and Knight, Chris},
abstractNote = {A detailed understanding of the inherently multiscale proton transport process raises a number of scientifically challenging questions. For example, there remain many (partially addressed) questions on the molecular mechanism for long-range proton migration and the potential for the formation of long-lived traps giving rise to burst-and-rest proton dynamics. Using results from a sizeable collection of ab initio molecular dynamics (AIMD) simulations (totaling ∼2.7 ns) with various density functional approximations (Becke-Lee-Yang-Parr (BLYP), BLYP–D3, Hamprecht-Cohen-Tozer-Handy, B3LYP) and temperatures (300–330 K), equilibrium and dynamical properties of one excess proton and 128 water molecules are studied. Two features in particular (concerted hops and weak hydrogen-bond donors) are investigated to identify modes in the system that are strongly correlated with the onset of periods of burst-and-rest dynamics. The question of concerted hops seeks to identify those time scales over which long-range proton transport can be classified as a series of sequential water hopping events or as a near-simultaneous concerted process along compressed water wires. The coupling of the observed burst-and-rest dynamics with motions of a fourth neighboring water molecule (a weak hydrogen-bond donor) solvating the protonated water molecule is also investigated. The presence (absence) of hydrogen bonds involving this fourth water molecule before and after successful proton hopping events is found to be strongly correlated with periods of burst (rest) dynamics (and consistent with pre-solvation concepts). By analyzing several realizations of the AIMD trajectories on the 100-ps time scale, convergence of statistics can be assessed. For instance, it was observed that the probability for a fourth water molecule to approach the hydronium, if not already proximal at the beginning of the lifetime of the hydronium, is very low, indicative of the formation of stable void regions. Furthermore, the correlations of the neighboring water atoms are identified as the fourth water approaches the hydronium. Finally, the temperature effects on structural and dynamical properties are studied.},
doi = {10.1063/1.4905077},
url = {https://www.osti.gov/biblio/22415450}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 1,
volume = 142,
place = {United States},
year = {Wed Jan 07 00:00:00 EST 2015},
month = {Wed Jan 07 00:00:00 EST 2015}
}

Works referencing / citing this record:

Recent advances in quantum‐mechanical molecular dynamics simulations of proton transfer mechanism in various water‐based environments
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Aqueous proton-selective conduction across two-dimensional graphyne
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Correlated dynamics in aqueous proton diffusion
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A simple and effective solution to the constrained QM/MM simulations
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Calculation of solvation free energy utilizing a constrained QM/MM approach combined with a theory of solutions
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Hydrated excess protons and their local hydrogen bond transport network as measured by translational, librational, and vibrational frequencies
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Entropic barriers in the kinetics of aqueous proton transfer
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Reactive molecular dynamics simulations of an excess proton in polyethylene glycol-water solutions
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Correlated Dynamics in Aqueous Proton Diffusion
text, January 2018


Aqueous proton-selective conduction across two-dimensional graphyne
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Predicting the Ionic Product of Water
journal, August 2017