To complete the picture, we checked for possible differences in the formation energy calculated via the symmetric 12-layer bulk unit cell (Fig. ) and that obtained for a stacked, asymmetric 6-layer bulk unit cell for the different Ag/Pt(111) systems (Fig. ). This 6-layer cell differs from that in Fig. in that in the previous case the asymmetric 6-layer unit cells were mirrored to form the symmetric 12-layer unit cell, while in the present they are sequentially stacked. The formation energies of the bimetallic unit cells were again calculated via eq. ( ). To correct for the different cell thicknesses, the energies of the stacked, asymmetric 6-layer cells are multiplied by 2. The resulting formation energies of the two different types of unit cells, which again include contributions from interface energies and compression energies, are plotted in Fig. and listed in Table . Obviously, there are clearly detectable differences between the formation energies of the stacked and the mirrored systems, which must be due to the different types and numbers of interfaces in the two cell types. These include 2 Ag -Ptrel interfaces (Ptrel : relaxed Pt) in the symmetric, mirrored 12-layer unit cell and 4 Ag -Ptfix interfaces (Ptfix : fixed Pt) in 2 unit cells with together 12 layers for the stacked, asymmetric unit cells. Also, the Ag -Ag bonds between Ag layers are replaced by Ag -Ptfix bonds. The compression energies, in contrast, should be identical in both cases, since in these calculations all Ag layers are pseudomorphic. Important to note is that the compression energies were mainly responsible for the increasing bulk formation energy from the Ag1L via the Ag2L to the Ag3L system. In summary, for the Ag-film systems the differences between symmetric 12-layer and stacked asymmetric 6-layer system are quite significant, relative to the absolute formation energies. Interestingly, for the Ag1L system the 6-layer stacked system is energetically more costly than the 12-layer system, indicating that Ag1L Ag2L Ag3L Pt@Ag1L Pt@Ag1L