Comparing Stockmayer Fluid Simulation and Experiment: Ion Solvation with Permanent Dipoles

The solvation of ions in polymer membranes has been studied over many decades. Nevertheless, an understanding of the solvation mechanism involves various computational challenges. This is primarily because molecular simulations for ion solvation that can simultaneously consider both atomic and molecular length scales are still significantly limited, even in cases of non-polymeric solvents. In this study, we developed a coarse-grained Stockmayer fluid simulation to address this issue, treating solvent molecules as soft-core spheres with permanent dipole moments. In this talk, we validate our model concept by considering monovalent and divalent ions dissolved in various non-polymeric solvents, such as water and methanol. Despite model simplicity, the results of our simulations show striking agreement when compared with experimental data for the free energy and enthalpy of ion solvation. We will also discuss that the primary contribution to the solvation energy arises mainly from the first and possibly second solvation shells near the ions.