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Title: Hydration structure of salt solutions from ab initio molecular dynamics

The solvation structures of Na{sup +}, K{sup +}, and Cl{sup -} ions in aqueous solution have been investigated using density functional theory (DFT) based Car-Parrinello (CP) molecular dynamics (MD) simulations. CPMD trajectories were collected for systems containing three NaCl or KCl ion pairs solvated by 122 water molecules using three different but commonly employed density functionals (BLYP, HCTH, and PBE) with electron correlation treated at the level of the generalized gradient approximation (GGA). The effect of including dispersion forces was analyzed through the use of an empirical correction to the DFT-GGA scheme. Special attention was paid to the hydration characteristics, especially the structural properties of the first solvation shell of the ions, which was investigated through ion-water radial distribution functions, coordination numbers, and angular distribution functions. There are significant differences between the present results obtained from CPMD simulations and those provided by classical MD based on either the CHARMM force field or a polarizable model. Overall, the computed structural properties are in fair agreement with the available experimental results. In particular, the observed coordination numbers 5.0-5.5, 6.0-6.4, and 6.0-6.5 for Na{sup +}, K{sup +}, and Cl{sup -}, respectively, are consistent with X-ray and neutron scattering studies but differ somewhat frommore » some of the many other recent computational studies of these important systems. Possible reasons for the differences are discussed.« less
Authors:
; ;  [1]
  1. Institute for Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States)
Publication Date:
OSTI Identifier:
22099162
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 138; Journal Issue: 1; Other Information: (c) 2013 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 74 ATOMIC AND MOLECULAR PHYSICS; ANGULAR DISTRIBUTION; ANIONS; APPROXIMATIONS; AQUEOUS SOLUTIONS; CATIONS; CHLORINE IONS; DENSITY FUNCTIONAL METHOD; ELECTRON CORRELATION; HYDRATION; ION PAIRS; MOLECULAR DYNAMICS METHOD; NEUTRON DIFFRACTION; POTASSIUM IONS; SIMULATION; SODIUM IONS; X-RAY DIFFRACTION