Rigorous treatment of electrostatics for spatially varying dielectrics based on energy minimization

TL;DR

This paper introduces a new energy minimization approach for electrostatics in systems with spatially varying dielectrics, enabling precise calculations of energy and forces without simplifying assumptions.

Contribution

It develops a novel integral equation-based formalism that accurately computes electrostatics in complex dielectric environments, applicable to biomolecular systems.

Findings

Achieves arbitrary accuracy in electrostatic calculations

Operates solely with volume charge distributions

Applicable to any spatial dielectric variation

Abstract

A novel energy minimization formulation of electrostatics that allows computation of the electrostatic energy and forces to any desired accuracy in a system with arbitrary dielectric properties is presented. An integral equation for the scalar charge density is derived from an energy functional of the polarization vector field. This energy functional represents the true energy of the system even in non-equilibrium states. Arbitrary accuracy is achieved by solving the integral equation for the charge density via a series expansion in terms of the equation's kernel, which depends only on the geometry of the dielectrics. The streamlined formalism operates with volume charge distributions only, not resorting to introducing surface charges by hand. Therefore, it can be applied to any spatial variation of the dielectric susceptibility, which is of particular importance in applications to biomolecular systems. The simplicity of application of the formalism to real problems is shown with analytical and numerical examples.