Irregularities at the {001} surface of MgO: Topography and other aspects

Non-planar sites (e.g. kinks, corners and ledges) are believed to be important in such processes as corrosion, catalysis and crystal growth, but it is difficult to obtain information about their surface relaxation or properties by experimental means. We have therefore studied them using theoretical methods, and present calculations on the topography of non-planar surface sites in the fcc materials MgO, CaO, NiO and NaCl. The models used in the calculations involved both cavities of vacancies within the planar surface and blocks of adatoms above it, and the validity of using such models is discussed. In addition, a more detailed study is undertaken for the doping of non-planar sites in MgO, and comparison is made with the bulk and at the planar {001} surface. Finally, a brief discussion of some thermal excitation energies, both in the planar surface and at selected irregularities in the non-planar surface, is given.