Mail:
Dept. of Chemistry
Ohio State University
100 W. 18th Ave.
Columbus, OH 43210
Office:
412 CBEC
Email:
herbert@
chemistry.ohio-state.edu
We propose a Debye-Hückel-like screening model (DESMO) that generalizes the familiar conductor-like screening model (COSMO) to solvents with non-zero ionic strength and furthermore provides a numerical generalization of the Debye-Hückel model that is applicable to non-spherical solute cavities. The numerical implementation of DESMO is based upon the switching/Gaussian (SWIG) method for smooth cavity discretization, which we have recently introduced in the context of polarizable continuum models (PCMs). This approach guarantees that the potential energy is a smooth function of the solute geometry and analytic gradients for DESMO are reported here. The SWIG formalism also facilitates analytic implementation of two other PCMs that are based on a screened Coulomb potential: the "integral equation formalism" (IEF-PCM) and the "surface and simulation of volume polarization for electrostatics" [SS(V)PE] method. Fully analytic implementations of these screened PCMs are reported here for the first time. Numerical results, for model systems where an exact solution of the linearized Poisson-Boltzmann equation is available, demonstrate that these screened PCMs are highly accurate. In realistic test cases, they are as accurate as the best available three-dimensional finite-difference methods. In polar solvents, DESMO is nearly as accurate as more sophisticated screened PCMs, but is significantly simpler and more efficient.