Molecular Density Functional Theory of Water

TL;DR

This paper introduces a first-principles molecular density functional theory for water that efficiently predicts microscopic solvation profiles around molecules, significantly reducing computational costs compared to explicit simulations.

Contribution

The paper develops a classical MDFT of water based on fundamental principles using density fields, requiring minimal input and enhancing computational efficiency.

Findings

Accurately predicts 3D solvation profiles around molecular solutes.

Requires only partial charge distribution and bulk properties as input.

Achieves 2-3 orders of magnitude reduction in computational cost.

Abstract

Three dimensional implementations of liquid state theories offer an efficient alternative to computer simulations for the atomic-level description of aqueous solutions in complex environments. In this context, we present a (classical) molecular density functional theory (MDFT) of water that is derived from first principles and is based on two classical density fields, a scalar one, the particle density, and a vectorial one, the multipolar polarization density. Its implementation requires as input the partial charge distribution of a water molecule and three measurable bulk properties, namely the structure factor and the k-dependent longitudinal and transverse dielectric constants. It has to be complemented by a solute-solvent three-body term that reinforces tetrahedral order at short range. The approach is shown to provide the correct three-dimensional microscopic solvation profile around various molecular solutes, possibly possessing H-bonding sites, at a computer cost two-three orders of magnitude lower than with explicit simulations.