Application of a two-length scale field theory to the solvation of charged molecules: I. Hydrophobic effect revisited

TL;DR

This paper develops a two-length scale self-consistent theory to describe hydrophobic interactions and solvation of charged molecules, comparing results with Monte-Carlo simulations and extending to electrostatic interactions.

Contribution

It introduces a novel continuous self-consistent framework for solute-water interactions that explicitly accounts for solvent structure and electrostatics.

Findings

The theory accurately predicts solvent density profiles and solvation free energies.

Comparison with Monte-Carlo data validates the model's effectiveness.

Extension to electrostatics shows consistency with classical continuous media theories.

Abstract

On a basis of a two-length scale description of hydrophobic interactions we develop a continuous self-consistent theory of solute-water interactions which allows to determine a hydrophobic layer of a solute molecules of any geometry with explicit account of solvent structure described by its correlation function. We compute the mean solvent density profile n(r) surrounding the spherical solute molecule as well as its solvation free energy. We compare the two-length scale theory to the numerical data of Monte-Carlo simulations found in the literature and discuss the possibility of a self-consistent adjustment of the free parameters of the theory. In the frameworks of the discussed approach we compute also the solvation free energies of alkane molecules and the free energy of interaction of two spheres separated by some distance. We describe the general setting of a self-consistent account of electrostatic interactions in the frameworks of the model where the water is considered not as a continuous media, but as a gas of dipoles. We analyze the limiting cases where the proposed theory coincides with the electrostatics of a continuous media.