Regularizing binding energy distributions and thermodynamics of hydration. Application to water modeled with classical and ab initio simulations

TL;DR

This paper introduces a method using external fields to regularize the binding energy distribution in solute-solvent systems, enabling more accurate calculation of excess free energy in water through classical and ab initio simulations.

Contribution

It presents a novel approach to modify energy distributions with external fields, improving free energy calculations for hydration in condensed systems.

Findings

Regularized binding energy distributions facilitate free energy calculations.

Method applied successfully to water with classical and ab initio models.

Enhanced understanding of hydration thermodynamics.

Abstract

The high-energy tail of the distribution of solute-solvent interaction energies is poorly characterized for condensed systems, but this tail region is of principal interest in determining the excess free energy of the solute. We introduce external fields centered on the solute to modulate the short-range repulsive interaction between the solute and solvent. This regularizes the binding energy distribution and makes it easy to calculate the free energy of the solute with the field. Together with the work done to apply the field in the presence and absence of the solute, we calculate the excess chemical potential of the solute. We present the formal development of this idea and apply it to study liquid water.