Locality and Fluctuations: Trends in lmidazolium-Based Ionic Liquids and Beyond

Three different imidazolitun-based ionic liquids, 1,3-dimethylimidazolium chloride, 1-ethyl-3-methylimidazolium thiocyanate, and 1-ethyl-3-methylimidazolium dicyanamide, are investigated by Car-Parinello simulations. A common behavior, such as a broad electric dipole moment distribution of the ions and a related high degree of locality, is found to characterize all these systems. Going beyond imidazolium-based systems, we found that even for the protic ionic liquid monomethyl ammonium nitrate, the same features hold. These results represent a strong support to the hypothesis of rattling ions in long-living ion cages proposed in the last years.