Electronic continuum correction without scaled charges

Abstract

In recent years the “Pandora's box” of charges used in classical simulations of nonpolarizable molecular models, especially for aqueous solutions and ionic liquids, has been opened. Particularly we refer to the Electronic continuum correction (ECC) model that suggests applying scaled down charges of ions and tearing down the ‘dogma’ of identical charges used to describe the potential energy surfaces (PES) and dipole moment surface (DMS). We elaborate on both ideas and integrate them into a consistent description of ‘real’ atomic charges of water and ions, which does not necessarily need to violate the ‘dogma’. We promote ECCε approach directly incorporating the electronic polarizability into screening of electrostatic interactions, avoiding the use of scaled charges, which perplex the comparison with experiment, ab initio or polarizable models and are cumbersome for interactions with external electric or magnetic fields. We conclude that none of the existing nonpolarizable water models is fully consistent with the continuum electronic polarizability and stimulate a quest for a better model implementing ECCε ideas.