A universal bridge functional for infinitely diluted solutions: A case study for Lennard-Jones spheres of different diameters

Abstract

We propose a universal bridge functional for closure of the Ornstein-Zernike (OZ) equation for infinitely diluted solutions of Lennard-Jones spheres of different sizes in a Lennard-Jones fluid. The bridge functional is parameterized using data from molecular dynamics (MD) simulations. We show that for all of the investigated systems, the bridge functional can be efficiently parameterized with an exponential function that depends only on the ratio of the sizes of solute and solvent atoms. To check the parameterization, we solve the OZ equation with a closure that includes the parametrized functional, and with a closure without the bridge functional (a hypernetted chain closure). We show that introducing the bridge functional allows us to obtain radial distribution functions (RDFs) close to the MD results, and to improve substantially predictions of the location and height of the first peak of an RDF.