Role of Viscosity in Deviations from the Nernst-Einstein Relation

Deviations from the Nernst-Einstein relation are commonly attributed to ion-ion correlation and ion-pairing. Despite the fact that these de- viations can be quantified by either experimental measurements or molecular dynamics simulations, there is no rule of thumb to tell the extent of deviations. Here, we show that deviations from the Nernst-Einstein relation is proportional to the inverse viscosity by exploring the finite-size effect on the transport properties in periodic boundary conditions. This conclusion is in accord with established experimental results of ionic liquids.