DIELECTRIC SCREENING TREATMENT OF ELECTROSTATIC SOLVATION

It has been shown previously that the solvation energies of small mole cules can be computed to useful accuracy with continuum models of the solvent that separate the solvation energy into electrostatic and nonp olar parts. The electrostatic part of the solvation energy can be comp uted with detailed solutions of the Poisson equation, but such calcula tions are time-consuming. This paper examines the reliability of an ap proximate method for computing electrostatic solvation energies within the continuum model. The central approximation is that, although the electrostatic field is weakened by the high-dielectric solvent, the sh ape of the field is not influenced by the solvent. This ''dielectric s creening'' approximation appears to work well when used with a nonline ar, lattice-based model of the solvent. Here, it is developed in the c ontext of linear, continuum electrostatics. The optimal screening func tion is found to depend upon the distribution of charge within the sol ute. The present dielectric screening method performs well in comparis ons with finite-difference solutions of the Poisson equation and with experimental data, for a range of molecular systems.