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Title: Dipolar correlations in liquid water

We present an analysis of the dipolar correlations in water as a function of temperature and density and in the presence of simple ionic solutes, carried out using molecular dynamics simulations and empirical potentials. We show that the dipole-dipole correlation function of the liquid exhibits sizable oscillations over nanodomains of about 1.5 nm radius, with several isosbestic points as a function of temperature; the size of the nanodomains is nearly independent on temperature and density, between 240 and 400 K and 0.9 and 1.3 g/cm{sup 3}, but it is substantially affected by the presence of solvated ions. In the same range of thermodynamic conditions, the decay time (τ) of the system dipole moment varies by a factor of about 30 and 1.5, as a function of temperature and density, respectively. At 300 K, we observed a maximum in τ as a function of density, and a corresponding shallow maximum in the tetrahedral order parameter, in a range where the diffusion coefficient, the pressure and the dielectric constant increase monotonically.
Authors:
 [1] ;  [2]
  1. Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States)
  2. Institute for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637 (United States)
Publication Date:
OSTI Identifier:
22419830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CORRELATION FUNCTIONS; DENSITY; DIFFUSION; DIPOLE MOMENTS; DIPOLES; LIQUIDS; MOLECULAR DYNAMICS METHOD; ORDER PARAMETERS; OSCILLATIONS; PERMITTIVITY; SIMULATION; SOLUTES; TEMPERATURE DEPENDENCE; WATER