Contrinuum Level treatment of electronic polarization in the framework of moleuclar simulations of solvation effects

摘要

The hybrid molecular-continuum mode for polar solvation considered in this paper combines the dielectric continuum approximation for treating fast electronic (inertialess)polarization effects and a molecular dynamics(MD)simulation of the slow (inertial)polarization component,including orientational and translational solvent modes.The inertial polarization is gneerated by average charge distributions of solvent particles,composed of permanent and induced (electronic) components.mD simulations are performed in a manner consistent with the choice of solvent and solute charges such that all electrostatic interactions are scaled by the factor 1/epsilon_infinity,where epsilon_infinity is the optica dielectric permittivity.This approach yields an ensemble of equilibrum solvent configurations adjusted to the electric field created by a charged or strongly polar solute.The electrostatic solvent responese field is found as the solution of the Poisson equation including both solute and explicit solvent charges,with accurate account of electrostatic boundary conditions at the surfaces separating spatial regions with different dielectric permittivities.Both equilibrium and nonequilibrium solvation effects can be studied by means of this model,and their inertial and inertialess contributions are naturally separated.the methodology for computation of charge transfer reorganization energies is developed and applied to a model two-site dpolar system in the SPC water solvent.Three types of change transfer reactios are considered.The standard linear-response approach yields high accuracy for each particulr reaction,but proves to be significantly in error when reorganization energies of different reaction were compared.This result has a purely melecular origin and is absent within a conventional continuum solvent model.