  One of the long standing challenges in molecular simulation is the
description of interfaces. On the molecular length scale, finite size effects
significantly influence the properties of the interface such as its interfacial
tension, which can be reliably investigated by molecular dynamics simulation of
planar vapor-liquid interfaces. For the Lennard-Jones fluid, finite size
effects are examined here by varying the thickness of the liquid slab. It is
found that the surface tension and density in the center of the liquid region
decreases significantly for thin slabs. The influence of the slab thickness on
both the liquid density and the surface tension is found to scale with 1/S^3 in
terms of the slab thickness S, and a linear correlation between both effects is
obtained. The results corroborate the analysis of Malijevsk\'y and Jackson, J.
Phys.: Cond. Mat. 24: 464121 (2012), who recently detected an analogous effect
for the surface tension of liquid nanodroplets.
