Keep in mind, however, that the exact value of β might also depend on the specific property we are looking at. The self-diffusion coefficients are obtained as cms-MSDs for individual molecules within system X, averaged over all molecules within X of the same molecular type. To treat systems with different mobility and size in a comparable fashion, the cms-MSDs are fitted always over a time interval between 0.03 × τ X and 0.4 × τ X , which is corresponding to a time interval between 15 ps and 200 ps for the reference water simulations. The width of the distribution of a quantity Y (X) (either true self-diffusion coefficient D 0 (X), or the viscosity η(X)) determined for the components in system X, obtained from a consecutive series of simulations is described by