We performed several calculations to test the performance of the parameters for a single cation. A distorted structure for the [5MIm] cation was generated where the ring was elongated by 30 % along the N1 atom and two methylene units were also distorted (see Supplementary Information). The geometry of this structure was optimized with Gaussian16 and TINKER to compare the final minimized coordinates. A similar analysis was performed for a series of 10 conformers of [di6Im] cation to investigate the larger conformational space allowed by the two alkyl chains. Figure shows the plot of [di6Im] with the relative energies of the studied conformers.