Molecular theory of solvation processes in dipolar and non-dipolar solvents

Abstract

We describe a molecular theory of solvation dynamics which provides a detailed description of the mechanism of solvent response following a sudden change in the charge distribution of a solute molecule. The theory is based on a new renormalized linear response development which incorporates nonlinear aspects of equilibrium solvation. The solute-solvent coupling is formulated in terms of intermolecular interactions, without recourse to macroscopic cavity concepts. Both the solute and solvent and solvent are represented by interaction site models, while the dynamical aspects are treated with our previously developed Reference Memory Function Approximation. The results for solvation dynamics in water and acetonitrile compare very favourably with MD simulation results for the same model systems. The same renormalized dynamical theory of solvation provides a very useful framework for estimating free energy profiles and associated parameters (average vertical energy gap, reorganization energy, change in solvation free energy) for electron transfer reactions. The new results demonstrate that a reasonably detailed molecular theory that deals with models incorporating the charge distribution of the molecules explains the solvation properties relevant to the theory of electron transfer reactions in both dipolar and non-dipolar (polar) solvents.