Figure shows the Soret coefficient of the studied Lennard-Jones mixtures for different system sizes (i.e., 1200 and 8000 molecules). As can be seen, there is a very good agreement between the Soret coefficient based on the simulations with 1200 molecules and those obtained from the simulations with 8000 molecules for the mixtures B and C. The peculiarly strong differences found for mixture A could be traced back to the use of a relatively short cutoff in the simulations with 1200 molecules. When the cutoff radius was changed to l/2, the agreement with the 8000 molecules simulation was significantly improved. A strong dependence of the cross-correlated phenomenological coefficient L E1 on the cutoff radius was found especially for mixture A1. Changes of other transport properties due to the cutoff radius (e.g., diffusion coefficients, shear viscosity, and thermal conductivity) were found to be within their statistical uncertainties. Negligible changes were also found for the thermodynamic equilibrium properties. Solely, the average pressure was 15% lower for the simulations with a smaller cutoff radius.