Abstract
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.
Highlights
In a world of hard-core numerical simulations on huge computers where most problems in solution chemistry are formulated in terms of molecular dynamics simulations and subsequent data analysis, it is wise to keep simpler methods that make it possible to derive analytical results or to perform the calculations with reasonable computer resources
The fact that, as noted by Chandler, the introduction of such hard-core boundaries modifies the apparent susceptibility of the medium outside the core is a consequence that applies to the LHNC-density functional theory (DFT) approach as it does for the Gaussian field theory (GFT) one
In this paper we have shown a close connection between the Gaussian field theory of solvation introduced by Chandler in [65] and density functional theory in a linearised hypernetted chain (HNC) approximation
Summary
In a world of hard-core numerical simulations on huge computers where most problems in solution chemistry are formulated in terms of molecular dynamics simulations and subsequent data analysis, it is wise to keep simpler methods that make it possible to derive analytical results or to perform the calculations with reasonable computer resources Such methods rely on the statistical mechanics of atomic and molecular liquids that has been developed in the second half of the last century and are found in classical textbooks [1,2,3]. We restrict the discussion to atomic or pseudo-atomic solvents (such as CCl4) modelled by spherical Lennard-Jones particles for which only the position r matters
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
