Molecular Dynamics Simulations of Ionic Liquids and Electrolytes Using Polarizable Force Fields

Abstract

Many applications in chemistry, biology, and energy storage/conversion research rely on molecular simulations to provide fundamental insight into structural and transport properties of materials with high ionic concentrations. Whether the system is comprised entirely of ions, like ionic liquids, or is a mixture of a polar solvent with a salt, e.g., liquid electrolytes for battery applications, the presence of ions in these materials results in strong local electric fields polarizing solvent molecules and large ions. To predict properties of such systems from molecular simulations often requires either explicit or mean-field inclusion of the influence of polarization on electrostatic interactions. In this manuscript, we review the pros and cons of different treatments of polarization ranging from the mean-field approaches to the most popular explicit polarization models in molecular dynamics simulations of ionic materials. For each method, we discuss their advantages and disadvantages and emphasize key assumptions as well as their adjustable parameters. Strategies for the development of polarizable models are presented with a specific focus on extracting atomic polarizabilities. Finally, we compare simulations using polarizable and nonpolarizable models for several classes of ionic systems, discussing the underlying physics that each approach includes or ignores, implications for implementation and computational efficiency, and the accuracy of properties predicted by these methods compared to experiments.

How Molecular Chiralities of Bis(mandelato)borate Anions Affect Their Binding Structures With Alkali Metal Ions and Microstructural Properties in Tetraalkylphosphonium Ionic Liquids

“…BMB] anions leading to their less efficient packing in heterogeneous IL matrices[10,13]. In addition, a good agreement is observed between experimental data and computational results for [P4,4,4,8 ][BMB] and [P6,6,6,14 ][BMB] ILs at all studied temperatures.…”

Superionic liquids in conducting nanoslits: A variety of phase transitions and ensuing charging behavior

“…It is known that ion polarizability can play an important role in formation of electrical double layes [57][58][59][60], and its bona fide modelling can be essential, particularly at high ion concentrations and for low dielectric media [58]. In our classical statistical-mechanical model, the conformational and electronic degrees of freedom (of ions), responsible for ion polarizability, are not considered explicitly, but enter the model only through the effective dielectric constant ε of the interior of a pore, see Eq.…”

Predicting Melting Points of Biofriendly Choline-Based Ionic Liquids with Molecular Dynamics

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