Polarization and charge transfer in the hydration of chloride ions

Research output: Contribution to journalArticlepeer-review

89 Scopus citations

Abstract

A theoretical study of the structural and electronic properties of the chloride ion and water molecules in the first hydration shell is presented. The calculations are performed on an ensemble of configurations obtained from molecular dynamics simulations of a single chloride ion in bulk water. The simulations utilize the polarizable AMOEBA force field for trajectory generation and MP2-level calculations are performed to examine the electronic structure properties of the ions and surrounding waters in the external field of more distant waters. The ChelpG method is employed to explore the effective charges and dipoles on the chloride ions and first-shell waters. The quantum theory of atoms in molecules (QTAIM) is further utilized to examine charge transfer from the anion to surrounding water molecules. The clusters extracted from the AMOEBA simulations exhibit high probabilities of anisotropic solvation for chloride ions in bulk water. From the QTAIM analysis, 0.2 elementary charges are transferred from the ion to the first-shell water molecules. The default AMOEBA model overestimates the average dipole moment magnitude of the ion compared to the quantum mechanical value. The average magnitude of the dipole moment of the water molecules in the first shell treated at the MP2-level, with the more distant waters handled with an AMOEBA effective charge model, is 2.67 D. This value is close to the AMOEBA result for first-shell waters (2.72 D) and is slightly reduced from the bulk AMOEBA value (2.78 D). The magnitude of the dipole moment of the water molecules in the first solvation shell is most strongly affected by the local water-water interactions and hydrogen bonds with the second solvation shell, rather than by interactions with the ion.

Original languageEnglish
Article number014502
JournalJournal of Chemical Physics
Volume132
Issue number1
DOIs
StatePublished - 2010
Externally publishedYes

Funding

We gratefully acknowledge the support of the NSF under Grant No. CHE-0709560 and the DOE Computational Science Graduate Fellowship (Grant No. DE-FG02-97ER25308, to D.M.R.) for the support of this work. We acknowledge the Ohio Supercomputer Center for a grant of computing time. We thank Marco Masia for comments on the paper.

FundersFunder number
DOE Computational Science
National Science FoundationCHE-0709560
Directorate for Mathematical and Physical Sciences0709560

    Fingerprint

    Dive into the research topics of 'Polarization and charge transfer in the hydration of chloride ions'. Together they form a unique fingerprint.

    Cite this