Ab initio study of MgO stoichiometric clusters on the MgO(0 0 1) flat surface

First-principles DFT calculations were performed to study molecular MgO stoichiometric flat clusters on the perfect MgO(0 0 1) surface. It is shown that a model description of their energetics could be provided within a very simple independent defect approximation with surface, step, corners and kinks. The formation energies of the first three defects are derived, respectively: Esu=0.50 eV/MgO, Est=0.88 eV/MgO, E4c=5.79 eV. The model applies even for very small cluster sizes (n⩾4). For large clusters kink and corner energy contributions tend to be negligible, reflecting the tendency towards a constant binding energy of a single molecule to large clusters independently of their geometry.