which only contain terms directly obtainable from DFT calculations. Using Equations ( ) and ( ) we calculated the surface energy γ of all copper oxide surfaces in their most stable magnetic configuration under O-poor and Orich conditions. The corresponding values are given in These correlations can also be observed in the surface phase diagrams shown in Figure , which illustrates the surface energy as a function of the oxygen chemical potential. While the surface energy of the stoichiometric surfaces is constant in the surface phase diagram, the surface energy of the Cu-excess surfaces increases with increasing oxygen chemical po-tential and the surface energy of the O-excess surfaces decreases with increasing oxygen chemical potential.