where r(t) = [r x (t), r y (t), r z (t)] represent the position of the center of mass of a molecule at time t and the r i (t) are its respective components in x-, y-, and z-direction. Here . . . denotes time-averaging as well as averaging over all molecules in the system belonging to a certain molecule type. All computed self-diffusion coefficients are determined from cms-MSD fits to system-specific time intervals, as discussed in section III.