Berlin 2008 – wissenschaftliches Programm
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SYEC: Symposium Exact-exchange and hybrid functionals meet quasiparticle energy calculations
SYEC 4: Exact-exchange and hybrid functionals meet quasiparticle energy calculations IV
SYEC 4.1: Vortrag
Freitag, 29. Februar 2008, 10:15–10:30, A 151
GW Method for f-electron Systems: Applications to CeO2 and ThO2 — •Hong Jiang1, Ricardo I. Gomez-Abal1, Xinzheng Li1, Patrick Rinke1,2, and Matthias Scheffler1 — 1Fritz-Haber-Institut der MPG, Berlin — 2University of California at Sant Barbara, CA 93106
Understanding the physics of f-electron systems is regarded as a great challenge in condensed-matter physics today. In many of these materials the strong localization of the f-electrons gives rise to large many-body exchange and correlation effects and in addition leads to severe self-interaction errors in the local-density approximation (LDA). Many-body perturbation theory in the GW approximation offers both a quasiparticle perspective and an exact treatment of exchange. It is therefore a promising approach for investigating these systems. In this work we apply the G0W0 method to CeO2 and ThO2, the “simplest” f-electron systems for which the LDA provides a qualitatively correct description, but underestimates band gaps significantly. For both materials, G0W0 based on LDA provides an accurate description for the fundamental (p-d) band gap. In CeO2, the highly localized f-states fall within the p-d gap; the G0W0 correction increases the p-f gap and reduces the f-band width considerably. The resultant density of states is in good agreement with experiments. In ThO2, the 5f-states are more delocalized and overlap with the Th-6d bands; the G0W0 correction shifts the 5f-bands more than 6d-bands, changing the density of unoccupied states considerably. Implications for general f-electron systems with partially filled f-shell are discussed.