Wannier functions and chemical bonding in a slab model: MgO(001) and TiO2(110) surfaces

摘要

For the first time Wannier functions are generated for systems with two-dimensional periodicity (slabs) and used for the surface charge distribution analysis. It is suggested to use bulk Wannier functions to estimate the slab thickness, needed for the convergence of the results. The (001)-surface of MgO and (110)-surface of TiO2 crystals are studied. The population analysis of the (001)-surface slab of MgO, based on Wannier-type atomic orbitals (WTAOs), demonstrates a purely ionic nature of chemical bonding on the studied crystalline surface. For TiO2 the WTAOs method gives the mixed ionic-covalent type of chemical bonding on the (110)-surface with the covalent component at the surface being larger than inside the slab. (c) 2005 Wiley Periodicals, Inc.