Figure 3: The energies of adsorption plotted versus the position of the d-band center for the studied surfaces. The surfaces with compressive strain are marked by squares; the surfaces with no strain are represented by circles, while the surfaces with tensile strain are marked by triangles. The empty symbols relate to Pd surfaces, while the full symbols relate to Pt surfaces. The best linear fits for platinum surfaces are given by solid lines, while the best linear fits for palladium surfaces are given by dashed lines. Positive values of mean the endothermic dissociative adsorption of H2 and vice versa.