Ab Initio Force Fields for Imidazolium-Based Ionic Liquids.

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Materials Science

Background:

• Alkylimidazolium-based ionic liquids (ILs) are crucial in various applications.
• Experimental data for IL properties like heats of vaporization and diffusion coefficients are often scarce or inconsistent.
• Accurate computational models are needed to understand IL behavior.

Purpose of the Study:

• To develop ab initio force fields for alkylimidazolium-based ILs.
• To predict key physical properties including density, heats of vaporization, diffusion, and conductivity.
• To elucidate physical trends in cohesive energy and their dependence on IL structure.

Main Methods:

• Development of ab initio force fields tailored for ILs.
• Utilizing molecular dynamics simulations to predict IL properties.
• Comparison of simulation results with available experimental data.

Main Results:

• The developed force fields predict IL density, heats of vaporization, diffusion, and conductivity in semiquantitative agreement with experimental data.
• Physical trends in liquid cohesive energy were illuminated, showing differences compared to trends derived from experimental heats of vaporization.
• The study highlights the challenges in accurately predicting IL dynamics due to statistical uncertainties and force field sensitivity.

Conclusions:

• The developed ab initio force fields provide a reliable tool for studying ILs.
• These force fields are valuable for understanding structure-property relationships in neat ILs, especially where experimental data is limited.
• The findings contribute to more accurate molecular dynamics predictions for IL systems.