Ionic velocities in an ionic liquid under high electric fields using all-atom and coarse-grained force field molecular dynamics.

Molecular dynamics has been used to estimate ionic velocities and electrical conductivity in the ionic liquid 1-ethyl-3-methylimidazolium/tetraflouroborate (EMIM-BF(4)). Both an all-atom and coarse grained force fields were explored. The simulations were carried out at high electric fields where one might expect the Wien effect to become important in conventional electrolytes and that effect is observed. While the original Wilson theory used to explain the Wien effect in conventional electrolytes does not work well for ionic liquids, a minor modification of the theory allowed it to be used to qualitatively describe the data. The two coarse-graining methods were noisier as expected, but result in a significant savings in computational cost.