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Molecular dynamics study of the structural and diffusivity of imidazolium-based ionic liquids

Zhenghao Zhu

Department of Chemical & Biomolecular Engineering, University of Tennessee

This page shows visualizations of the systems consisting of 200 ions pairs of [C4mim+][NO3-] and [C4mim+][Tf2N-].

Molecular dynamics simulations are used to investigate the structure and dynamics of the ionic liquid, 1-n-butyl-3-methylimidazolium ([C4mim+]) with [NO3-] and [Tf2N-] at the temperature of 500 K. The structures were studied via the cation-cation, cation-anion, and anion-anion radial distribution functions of the ILs. And it shows that the bulk structure characteristics are very similar to those obtained from the quantum calculations. For two ILs, the cation-anion RDF shows a strong first peak at 4.5-5.5 Å, indicating a preferential cation-anion interaction over anion-anion and cation-cation interactions. The self-diffusivity coefficients of the cations and the anions were predicted from the mean-square-displacement (MSD) of the center of ions using the Einstein relation, and it shows that the cation has a higher self-diffusivity than its partner anion, even the anion is smaller than the cation, which is consistent with the previously reported experimental results. Additionally, it is noted that the ILs exhibit glassy dynamics behavior with a relatively short time.

Interactive Structures

  • Left: [C4mim+][NO3-]
  • Right: [C4mim+][Tf2N-]


  • [1] Hongjun Liu and Edward Maginn. J. Chem. Phys. 135, 124507 (2011).
  • [2] Gorgia-Evangelia Logotheti, Javier Ramos, and Ioannis G. Economou. J. Chem. Phys. B 113, 7211 (2009).

posted: April 2018.
updated: April 2018.