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Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-36025

Weber, V; Merchant, S; Dixit, P D; Asthagiri, D (2010). Molecular packing and chemical association in liquid water simulated using ab initio hybrid Monte Carlo and different exchange-correlation functionals. Journal of Chemical Physics, 132(20):204509.

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Abstract

In the free energy of hydration of a solute, the chemical contribution is given by the free energy required to expel water molecules from the coordination sphere and the packing contribution is given by the free energy required to create the solute-free coordination sphere (the observation volume) in bulk water. With the simple point charge/extended (SPC/E) water model as a reference, we examine the chemical and packing contributions in the free energy of water simulated using different electron density functionals. The density is fixed at a value corresponding to that for SPC/E water at a pressure of 1 bar. The chemical contribution shows that water simulated at 300 K with BLYP is somewhat more tightly bound than water simulated at 300 K with revised PBE (revPBE) functional or at 350 K with the BLYP and BLYP-D functionals. The packing contribution for various radii of the observation volume is studied. In the size range where the distribution of water molecules in the observation volume is expected to be Gaussian, the packing contribution is expected to scale with the volume of the observation sphere. Water simulated at 300 K with the revPBE and at 350 K with BLYP-D or BLYP conforms to this expectation, but the results suggest an earlier onset of system size effects in the BLYP 350 K and revPBE 300 K systems than that observed for either BLYP-D 350 K or SPC/E. The implication of this observation for constant pressure simulations is indicated. For water simulated at 300 K with BLYP, in the size range where Gaussian distribution of occupation is expected, we instead find non-Gaussian behavior, and the packing contribution scales with surface area of the observation volume, suggesting the presence of heterogeneities in the system. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3437061]

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Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
DDC:540 Chemistry
Language:English
Date:2010
Deposited On:23 Dec 2010 12:38
Last Modified:05 Jun 2014 13:50
Publisher:American Institute of Physics
ISSN:0021-9606
Additional Information:Copyright 2010 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Chem. Phys. 132, 204509 (2010) and may be found at http://dx.doi.org/10.1063/1.3437061
Publisher DOI:10.1063/1.3437061
Related URLs:http://arxiv.org/abs/1004.3223v1
PubMed ID:20515102

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