Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 67: Ab-initio approaches to excitations in condensed matter III
O 67.1: Vortrag
Freitag, 27. März 2009, 11:15–11:30, SCH 251
Tackling localized d-states: a systematic investigation by GW@LDA+U — •Hong Jiang1, Ricardo I. Gomez-Abal1, Patrick Rinke2,1, and Matthias Scheffler1,2 — 1Fritz-Haber-Institut der MPG, Berlin — 2University of California at Sant Barbara, CA 93106
First-principles modeling of systems with localized d-states is currently a great challenge in condensed matter physics. Density-functional theory (DFT) in the standard local-density approximation (LDA) proves to be problematic. This can be partly overcome by including local Hubbard U corrections (LDA+U), but itinerant states are still treated on the LDA level. Many-body perturbation theory in the GW approach offers both a quasiparticle perspective (appropriate for itinerant states) and an exact treatment of exchange (appropriate for localized states), and is therefore promising for these systems. Here we present a systematic investigation of the G0W0 method based on LDA+U (G0W0@LDA+U) for a series of prototype systems: 1) ZnS with semicore d-states, 2) ScN and TiO2 with empty d-states and 3) late transition metal oxides (MnO, FeO, CoO and NiO) with partially occupied d-states. We show that for ZnS, ScN and TiO2, the G0W0 band gap only weakly depends on U, but for the other transition metal oxides the dependence on U is as strong as in LDA+U. These different trends can be understood in terms of changes in the hybridization and screening. Our work demonstrates that G0W0@LDA+U with “physical” values of U provides a balanced and accurate description of both localized and itinerant states.