it is the high surface energy of Pt(111) which is responsible for the negative character of the slab formation energies. In other words, the pronounced change in surface energy, which is present in the slab formation energy, but not in the bulk formation energy, is responsible for the pronounced difference between (positive) bulk formation energies and (negative) slab formation energies in the Ag/Pt(111) systems. . Generally, the trends are rather similar, but with differences in the absolute values and in specific systems. The bulk formation energies are mostly slightly lower than for the corresponding Ag/Pt(111) systems, and some are even negative. Also here, the bulk formation energies increase with increasing Ag film thickness, and the increase is more pronounced than for the Ag/Pt(111) systems. This is mostly due to the larger contribution of the compression energies, which are caused by the slightly smaller lattice constant of Pd(111) compared to Pt(111). Although the difference is small, the effect on the compression energy is significant. On the other hand, the bulk formation energy of the Ag1L system is even negative for Ag/Pd(111), while it is positive for Ag/Pt(111). This is due to the much larger (negative) interface energy in the Ag/Pd(111) system. In fact, the interface energies are generally larger (and negative) in the Ag/Pd(111) systems than in the Ag/Pt(111) systems, by about a factor of 2, reflecting the tendency for intermixing due to a relatively stronger Pd-Ag bonding. This further supports our above conclusion of stronger interactions between Ag and Pd than between Ag and Pt, relative to the Pd -Pd (Pt -Pt) interactions and Ag -Ag interactions. Based on these trends, we would expect a higher tendency for intermixing (alloy formation) in the Ag/Pd(111) system than for the Ag/Pt(111) system, which is fully consistent with experimental observations. Finally, different from Ag/Pt(111), the bulk formation energies of the Pd/Ag1L surface alloys are not higher than those of the Ag1L film system, but lower. This results from the lower compression energy in the surface alloys than in Ag1L, in combination with similar size interface energies.