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Halide Ion Micro-Hydration: Structure, Energetics, and Spectroscopy of Small Halide–Water Clusters

preprint
submitted on 27.01.2019 and posted on 28.01.2019 by Pushp Bajaj, Marc Riera, Jason K. Lin, Yaira E. Mendoza Montijo, Jessica Gazca, Francesco Paesani

Replica exchange molecular dynamics simulations and vibrational spectroscopy calculations are performed using halide-water many-body potential energy functions to provide a bottom-up analysis of the structures, energetics, and hydrogen-bonding arrangements in X−(H2O)n=3−6 clusters, with X = F, Cl, Br, and I. Independently of the cluster size, it is found that all four halides prefer surface-type structures in which they occupy one of the vertices in the underlying three-dimensional hydrogen-bond networks. For fluoride-water clusters, this is in contrast with previous reports suggesting that fluoride prefers interior-type arrangements, where the ion is fully hydrated. These differences can be ascribed to the variability in how various molecular models are capable to reproduce the subtle interplay between halide-water and water-water interactions. Our results thus emphasize the importance of a correct representation of individual many-body contributions to the molecular interactions for a quantitative description of halide ion hydration.

Funding

National Science Foundation

Air Force Office of Scientific Research

History

Email Address of Submitting Author

fpaesani@ucsd.edu

Institution

University of California, San Diego

Country

United States

ORCID For Submitting Author

0000-0002-4451-1203

Declaration of Conflict of Interest

No conflict of interest

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