Dielectric response of the water hydration shell of an ion: a field theory approach

TL;DR

This paper introduces a continuous field theory model that captures the dielectric behavior of water at nanometric scales, accounting for saturation effects and molecular correlations crucial for electrolyte modeling.

Contribution

It proposes a novel electrostatic energy functional with non-local and nonlinear terms to accurately describe water's dielectric response at small scales.

Findings

Reproduces saturation of water's polarization response.

Captures nanometric dipolar correlations.

Modifies long-range van der Waals interactions.

Abstract

The goal of this work is to propose a simple continuous model that captures the dielectric properties of water at the nanometric scale. We write an electrostatic energy as a functional of the polarisation field containing a term in $P^4$ and non-local Gaussian terms. Such an hamiltonian can reproduce two key properties of water: the saturation of the polarisation response of water in the presence of a strong electrostatic field and the nanometric dipolar correlations of the solvent molecules modifying the long range van der waals interaction. This model explores thus two fundamental aspects that have to be included in implicit models of electrolytes for a relevant description of electrostatic interactions at nanometric scales.