Coarse-Grained Force Field for Imidazolium-Based Ionic Liquids.

Area of Science:

• Computational Chemistry
• Materials Science
• Chemical Engineering

Background:

• Ionic liquids (ILs) are crucial in various chemical processes.
• Accurate molecular simulations are vital for understanding IL behavior.
• Current simulation methods can be computationally expensive.

Purpose of the Study:

• To develop coarse-grained force fields (CGFFs) for imidazolium-based ionic liquids.
• To achieve computationally efficient and accurate molecular simulations.
• To reproduce both structural and thermodynamic properties of ILs.

Main Methods:

• Systematic coarse-graining approach using the relative entropy (RE) method.
• Constrained RE minimization with Lagrange multipliers to reproduce thermodynamic properties like pressure.
• Boltzmann inversion for bonded interactions; constrained RE for non-bonded and electrostatic interactions.

Main Results:

• CG models accurately predict structure and pressure for varying alkyl chain lengths.
• Simulations show agreement with all-atom molecular dynamics at various thermodynamic states.
• Dynamical properties, including diffusion, are preserved, reflecting cation-anion dynamics.

Conclusions:

• The developed CGFFs offer a computationally efficient and accurate method for IL simulations.
• The methodology successfully reproduces key structural and thermodynamic properties.
• This approach is applicable to other soft-matter systems and long-range electrostatic interactions.