with N + and N -being the number of cations and anions, and D + and D -being their selfdiffusion coefficients, respectively. Recently, Shao et al. demonstrated that for MD simulations with (cubic) periodic boundary conditions, the Green-Kubo (and, alternatively, Einstein-Helfland) conductivities are systemsize independent, whereas the Nernst-Einstein conductivities exhibit a strong system-size effect. This implies that the cross-correlations must exhibit finite-size effects that exactly compensate the finite-size effect of the diffusivity. Diddens and Heuer recently argued that this effect is due to hydrodynamic interactions and could be explained by describing the distance dependence of pair diffusion in periodic systems. To compute the Nernst-Einstein conductivities σ NE , we therefore rely on the systemsize independent self-diffusion coefficients D 0 as obtained from OrthoBoXY simulations, where available.