Condensed Matter Physics, 2017, vol. 20, No. 3, 33005
DOI:10.5488/CMP.20.33005
Title:
Solvation in atomic liquids: connection between Gaussian field theory and density functional theory
Author(s):

V. Sergiievskyi
(Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, UMR 8640 PASTEUR, 75005 Paris, France)
,


M. Levesque
(Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, UMR 8640 PASTEUR, 75005 Paris, France)
,


B. Rotenberg
(Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234 PHENIX, 4 Place Jussieu, 75005 Paris, France)
,


D. Borgis
(Sorbonne Universités, UPMC Univ Paris 06, ENS, CNRS, UMR 8640 PASTEUR, 75005 Paris, France; Maison de la Simulation, CEA, CNRS, Univ. ParisSud, UVSQ, Université ParisSaclay,
91191 GifsurYvette, France)

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 LennardJones solute of increasing size in a LennardJones solvent. Compared to MonteCarlo simulations,
all those theories give acceptable results for the inhomogeneous solvent structure, but are completely outofrange for the solvation freeenergies. This can be fixed in DFT by adding a
hardsphere bridge correction to the HNC functional.
Key words:
statistical mechanics, classical fluids, 3dimensional systems, density functional theory, gaussian field theory
PACS:
05.20.Jj, 11.10.z, 82.60.Lf, 64.75.Bc
