Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MM: Fachverband Metall- und Materialphysik

MM 51: Computational Materials Modelling VII - Oxides

MM 51.1: Vortrag

Donnerstag, 29. März 2012, 11:45–12:00, TC 006

Structural and electronic properties of oxides within a transferable tight binding model — •Alessandro Parma, Georg H. K. Madsen, and Ralf Drautz — ICAMS Ruhr-Universität Bochum, Stiepeler Strasse 129, 44801 Bochum, Germany

Using the Tight Binding (TB) approximation charge transfer and magnetism as well as covalent bonding can be modelled. Thereby a TB approximation is obtained by a systematic coarse graining of the density functional theory energy functional. We have implemented an orthogonal pd TB model for transition metal oxides. The optimized minimal basis is obtained by downfolding a multiple-ζ LCAO basis. The bond integrals within the two center approximation are then calculated from a down-folded DFT Hamiltonian. They are found to be continuous and transferable, and allow for a parametrization of the bond energy in terms of exponential functional forms. We use a Stoner model for the inclusion of magnetism and charge transfer is approximated by monopole interactions.

We present the common oxide structures in terms of simple building blocks and analyze them within a close packing approach. Their stability is calculated across the transition metal series and is rationalized in terms of covalent bonding, atomic volume and electronegativity using simple TB models. The Hematite and Wüstite structures are presented in special detail.