Molecular density functional theory of water including density-polarization coupling

TL;DR

This paper develops a three-dimensional molecular density functional theory for water that incorporates density-polarization coupling, using only partial charges and bulk properties, providing a more tractable and physically insightful model.

Contribution

It introduces a first-principles MDFT for water that includes density-polarization coupling and relies on minimal measurable properties, enhancing physical understanding and computational efficiency.

Findings

Includes full density-polarization coupling in water modeling

Uses only partial charge distribution and bulk properties

Offers more physical insight and tractability

Abstract

We present a three-dimensional molecular density functional theory (MDFT) of water derived from first-principles that relies on the particle's density and multipolar polarization density and includes the density-polarization coupling. This brings two main benefits: ($i$) a scalar density and a vectorial multipolar polarization density fields are much more tractable and give more physical insight than the full position and orientation densities, and ($ii$) it includes the full density-polarization coupling of water, that is known to be non-vanishing but has never been taken into account. Furthermore, the theory requires only the partial charge distribution of a water molecule and three measurable bulk properties, namely the structure factor and the Fourier components of the longitudinal and transverse dielectric susceptibilities.