Analyzing Dielectric Constants and Electrostatic Energies of Ionic Liquids: Mean-Field Theory and Stockmayer Fluid Simulation

Fully atomistic molecular dynamics simulations of ionic liquids with long-range, multi-body electrostatic interactions can often pose computational and statistical challenges, especially when ionic liquids are polymerized. To address this challenge while minimizing model complexity, we have developed a coarse-grained Stockmayer fluid model. This model characterizes ionic liquid ions as charged dipolar spheres and incorporates dielectric response considerations. Our model also demonstrates strong agreement with the experimental dielectric constants of various ionic liquids. We discuss the significance of factors such as the ionic size, dielectric saturation, electrostatic correlations, and first co-ordination shell for the simulated energy of ionic liquids. Additionally, we demonstrate that a mean-field energy equation can effectively account for our simulation results.