Condensed Matter Physics, 2017, vol. 20, No. 3, 33005
DOI:10.5488/CMP.20.33005
arXiv:1708.01299
Title:
Solvation in atomic liquids: connection between Gaussian field theory and density functional theory
Author(s):
 
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V. Sergiievskyi
(Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, UMR 8640 PASTEUR, 75005 Paris, France)
,
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M. Levesque
(Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, UMR 8640 PASTEUR, 75005 Paris, France)
,
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B. Rotenberg
(Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234 PHENIX, 4 Place Jussieu, 75005 Paris, France)
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D. Borgis
(Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, UMR 8640 PASTEUR, 75005 Paris, France; Maison de la Simulation, CEA, CNRS, Univ. Paris-Sud, UVSQ, Université Paris-Saclay,
91191 Gif-sur-Yvette, France)
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For the problem of molecular solvation, formulated as a liquid submitted to the external potential field created by a molecular solute of arbitrary shape dissolved in that solvent,
we draw a connection between the Gaussian field theory derived by David Chandler [Phys. Rev. E, 1993, 48, 2898] and classical density functional theory. We show that Chandler's
results concerning the solvation of a hard core of arbitrary shape can be recovered by either minimising a linearised HNC functional using an auxiliary Lagrange multiplier field to impose a
vanishing density inside the core, or by minimising this functional directly outside the core — indeed a simpler procedure. Those equivalent approaches are compared to two other variants of
DFT, either in the HNC, or partially linearised HNC approximation, for the solvation of a Lennard-Jones solute of increasing size in a Lennard-Jones solvent. Compared to Monte-Carlo simulations,
all those theories give acceptable results for the inhomogeneous solvent structure, but are completely out-of-range for the solvation free-energies. This can be fixed in DFT by adding a
hard-sphere bridge correction to the HNC functional.
Key words:
statistical mechanics, classical fluids, 3-dimensional systems, density functional theory, gaussian field theory
PACS:
05.20.Jj, 11.10.-z, 82.60.Lf, 64.75.Bc
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