Screening of Point charges in dielectrics: Disentangling Coulombic from Entropic effects.*

The  free energy of ion solvation of different solvent models can be decomposed  into enthalpic and entropic contributions. This can help our understanding of the dielectric properties of the solvent and their connection to the physical properties of the  underlying model. In an effort to model the effects of charge screening on ion pair stability, we present a linear response model that modifies the Coulomb potential and gives an alternate understanding of solvation transition barriers. Moreover, it predicts stable Coulombic pairings between like-charged ions. We show that this is a universal behavior associated to the non local response function of any dielectric or metallic system.