Energies relevant for metal-on-metal heteroepitaxial growth are calculated for a few selected systems using the effective-medium theory and a Green’s function technique within the tight-binding linear muffin-tin orbitals method. The two methods show good agreement with each other, lending support to the accuracy of the effective-medium modeling. The energetics of surface segregation and surface alloy formation are investigated and compared to simple estimates often used in this context. Quantitative as well as qualitative deviations from the simplest picture are found showing that more accurate models are necessary.