Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 78: Symposium Density functional theory and beyond for real materials

O 78.3: Hauptvortrag

Donnerstag, 25. März 2010, 15:45–16:15, H1

Localized and itinerant states in d/f-electron systems unified by GW@LDA+U — •Hong Jiang — College of Chemistry, Peking University, Beijing 100871, China

Density-functional theory in the local-density or generalized gradient approximation (LDA/GGA) has proven to be inadequate for d and f-electron systems that are characterized by the simultaneous presence of itinerant and localized states and interactions between them. The simplest extension that can overcome the major failure of LDA is the introduction of a local Hubbard-like correction (LDA+U), however itinerant states are still treated at the LDA level. As a first step towards a unified treatment of localized and itinerant states, we combine many-body perturbation theory in the GW approximation with LDA+U (GW@LDA+U) to investigate the quasiparticle band structure of prototypical d/f-electron systems. We observe good agreement between the GW density of states and experimental photoemission spectra using Us determined by constrained DFT. All main features in the experimental band gaps of the lanthanide sesquioxide series (Ln₂O₃) are well reproduced by GW@LDA+U and can be attributed to the evolution of the occupied and unoccupied f-states as the number of f-electrons increases. Consistent with other GW approaches, the satellite structure in late transition metal oxides is still absent, and the binding energy of occupied d/f-states exhibits a tendency to be underestimated. The implications of our studies for strongly correlated electrons are discussed. ^*In collaboration with R. I. Gomez-Abal, P. Rinke and M. Scheffler at Fritz-Haber-Institut der MPG.