The charge-asymmetric nonlocally-determined local-electric (CANDLE) solvation model

TL;DR

The paper introduces CANDLE, a new continuum solvation model that accurately captures solvent effects, including charge asymmetry, using a nonlocal cavity functional based on both electron density and potential, with minimal parameters.

Contribution

It presents the CANDLE model, a novel solvation approach that improves accuracy and generality by incorporating nonlocal and potential-dependent cavity definitions.

Findings

Achieves 1.8 kcal/mol mean absolute error in water

Reproduces solvation energies for neutral, cationic, and anionic molecules

Uses only three parameters per solvent

Abstract

Many important applications of electronic structure methods involve molecules or solid surfaces in a solvent medium. Since explicit treatment of the solvent in such methods is usually not practical, calculations often employ continuum solvation models to approximate the effect of the solvent. Previous solvation models either involve a parametrization based on atomic radii, which limits the class of applicable solutes, or based on solute electron density, which is more general but less accurate, especially for charged systems. We develop an accurate and general solvation model that includes a cavity that is a nonlocal functional of both solute electron density and potential, local dielectric response on this nonlocally-determined cavity, and nonlocal approximations to the cavity-formation and dispersion energies. The dependence of the cavity on the solute potential enables an explicit treatment of the solvent charge asymmetry. With only three parameters per solvent, this `CANDLE' model simultaneously reproduces solvation energies of large datasets of neutral molecules, cations and anions with a mean absolute error of 1.8 kcal/mol in water and 3.0 kcal/mol in acetonitrile.