k-space decomposition of the vacuum density of states (DOS) of a pseudomorphic Co ML on the Pt(111) surface. The results for fcc and hcp stacking (top and central panels, respectively) of the Co ML at two different energies are shown. The difference between the DOS corresponding to the two stackings (bottom panels) points out that at -0.250 eV (left) the hcp-DOS is the largest, while at -0.175 eV (right) the fcc-DOS dominates. This difference in the electronic structure for different stackings originates a spectroscopic shift, as it was revealed by scanning tunneling spectroscopy measurements (PRB 74, 195411 (2006)).