The density profiles for pure water in slab geometry are shown in Fig. for the FG reference system (s max = 1) and the AdSoS setups (s max = 1.5 or 2). In the scaled systems without biasing potential (Fig. ), two kinds of density artifacts can be observed. The first kind consists of sinusoidal fluctuations in the SG region. These fluctuations do not decrease with increasing cutoff, and they can also be observed in the much simpler case of liquid argon with minimum-image cutoff. This effect most likely results from the non-vanishing s-gradient in the SG region. The second kind of artifact is the density mismatch between the FG and CG regions. In contrast to the fluctuations in the SG region, the effect is reduced upon increasing the cutoff. A possible cause for this mismatch is that the effective cutoff s -1 R c is smaller for the CG than for the FG particles. Consequently, the FG atoms are experiencing stronger attractive dispersive interactions, leading to a higher density in the FG region. Note that these two artifacts remain limited in magnitude, with density variations on the order of ± 5% across the computational box. Mat Figures and, respectively. The LEUS weights are well converged after about 10 ns.