Density maximum and polarizable models of water

Péter T. Kiss, A. Baranyai

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

To estimate accurately the density of water over a wide range of temperatures with a density maximum at 4 °C is one of the most stringent tests of molecular models. The shape of the curve influences the ability to describe critical properties and to predict the freezing temperature. While it was demonstrated that with a proper parameter fit nonpolarizable models can approximate this behavior accurately, it is much more difficult to do this for polarizable models. We provide a short overview of ρ-T diagrams for existing models, then we give an explanation of this difficulty. We present a version of the BK model A. Baranyai and P. T. Kiss, J. Chem. Phys. 133, 144109 (2010)10.1063/1.3490660; A. Baranyai and P. T. Kiss, J. Chem. Phys. 135, 234110 (2011)10.1063/1.3670962 which is capable to predict the density of water over a wide range of temperature. The BK model uses the charge-on-spring method with three Gaussian charges. Since the experimental dipole moment and the geometry is fixed, and the quadrupole moment is approximated by a least mean square procedure, parameters of the repulsion and dispersive attraction forces remained as free tools to match experimental properties. Relying on a simplified but plausible justification, the new version of the model uses repulsion and attraction as functions of the induced dipole moment of the molecule. The repulsive force increases, while the attractive force decreases with the size of the molecular dipole moment. At the same time dipole moment dependent dispersion forces are taking part in the polarization of the molecule. This scheme iterates well and, in addition to a reasonable density-temperature function, creates dipole distributions with accurate estimation of the dielectric constant of the liquid.

Original languageEnglish
Article number084506
JournalThe Journal of Chemical Physics
Volume137
Issue number8
DOIs
Publication statusPublished - Aug 28 2012

Fingerprint

Dipole moment
Water
dipole moments
water
attraction
Temperature
Molecules
temperature
Freezing
freezing
molecules
Permittivity
quadrupoles
diagrams
Polarization
permittivity
dipoles
moments
Geometry
Liquids

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Density maximum and polarizable models of water. / Kiss, Péter T.; Baranyai, A.

In: The Journal of Chemical Physics, Vol. 137, No. 8, 084506, 28.08.2012.

Research output: Contribution to journalArticle

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