The dielectric self-consistent field method. I. Highways, byways, and illustrative results

Abstract

The dielectric self-consistent field method (DSCF) provides a continuum electrostatics tool to study the effects which the use of modified electrostatic interactions has on the properties of a solute–solvent system in molecular dynamics or Monte Carlo simulations with explicit solvent. The theoretical foundation and the implementation of the method are described. Results of calculations for small solutes, water and a spherical ion, are presented. The properties studied include the electrostatic contribution to the solvation free energy and solute–solvent orientational correlation functions. The information obtained in this manner turns out to be complementary and provides a broader basis for a critical comparison of widely used modified electrostatic interactions. We also compute the potential-of-mean-force for a pair of spherical ions of opposite charge. Among the modified electrostatic interactions compared [spherical truncation, a shifted potential, a generalized reaction field, and Ewald summation (EW)], EW is found to give the most consistent results compared with the true 1/r Coulomb potential. The paper concludes with a comparison of DSCF to related continuum electrostatic based approaches, such as numerical solutions of the Poisson–Boltzmann equation and the method of Langevin dipoles.