Finally, we would like to note that all calculations were performed for pseudomorphic overlayer systems, even though experimentally only Ag monolayer films remain pseudomorphic, while for bilayer and thicker films strain relief results in the formation of a unidirectionally expanded (striped) phase or, upon annealing, in a trigonal incommensurate phase, where strain is relieved isotropically. Despite of these structural differences, the data derived here provide detailed insight in trends in the stability of the different configurations. , those for RPBE/PAW in Table in the ESI. Furthermore, the formation enthalpies are plotted in Figure as a function of the Ag content in the surface layer, including also higher Pt concentrations.