Energy correction to simulation of volume polarization in reaction field theory

Reaction field theory is useful in electronic structure calculations of solute properties to evaluate the effects of long-range electrostatic interactions with solvent. The reaction field is affected by quantum mechanical penetration of solute charge density outside the surface of the solvent cavity that nominally encloses it. Exact treatment of the effect of this charge penetration is possible, within the context of a simple dielectric continuum model, by invoking a certain volume polarization in addition to the usually treated surface polarization. However, with general nonspherical molecular cavities this is difficult and computationally demanding to handle, so more tractable means to optimally simulate or otherwise approximate the effect of volume polarization in terms of modified surface polarization are useful in practice. This work proposes and tests a simple formula for a correction term to estimate the energy difference between exact treatment of volume polarization and its optimal surface simulation. (C) 2002 American Institute of Physics.