Exact relations between charge-density functions determining the total Coulomb energy and the dielectric constant for a mixture of neutral and charged site-site molecules

TL;DR

This paper derives exact relations linking charge-density functions to the dielectric constant and Coulomb energy in mixtures of neutral and charged molecules, extending previous models and aiding thermodynamic corrections.

Contribution

It provides a unified derivation connecting ion moment conditions to dielectric properties and offers exact expressions for charge-density functions in mixed molecular systems.

Findings

Exact relations between charge-density functions and dielectric constant.

Derived small-k expansion expressions for Coulomb energy calculations.

Facilitates thermodynamic corrections for truncated Coulomb interactions.

Abstract

We extend results developed by Chandler [J. Chem. Phys. 65, 2925 (1976)] for the dielectric constant of neutral site-site molecular models to mixtures of both charged and uncharged molecules. This provides a unified derivation connecting the Stillinger-Lovett moment conditions for ions to standard results for the dielectric constant for polar species and yields exact expressions for the small-k expansion of the two-point intermolecular charge-density function used to determine the total Coulomb energy. The latter is useful in determining corrections to the thermodynamics of uniform site-site molecular models simulated with spherically truncated Coulomb interactions.