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Patrick Rinke(a), Hong Jiang(a,b), R. Gómez-Abal(a), Matthias Scheffler(a)
(a) Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany (b) College of Chemistry, Peking University, China The accurate first-principles description of d- and f-electron systems is currently regarded as one of the great challenges in condensd matter physics due to the simultaneous presence of itinerant (delocalized) and highly localized states and interactions between them. Focusing on the spectral properties of the lanthanide sesquioxide series (Ln2O3) we apply many-body perturbation theory in the G0W0 approach based on LDA+U ground state calculations (G0W0@LDA+U) [1]. Our first principles G0W0 calculations offer both a quasi-particle perspective (appropriate for itinerant states) and an exact treatment of exchange (appropriate for localized states). We observe good agreement between the G0W0 density of states (DOS) and experimental spectra, however, the binding energy of occupied f-states tends to be underestimated consistent with previous GW calculations for d-electron binding energies [2]. For the whole Ln2O3 series G0W0@LDA+U reproduces all main features found for the optical experimental band gaps [1]. Inspection of the DOS reveals that the relative positions of the occupied and unoccupie f-states predicted by G0W0 confirm the experimental conjecture derived from phenomenological arguments. We also compare GW@LDA+U to other variants of the GW approach as well as dynamical mean-field theory (DMFT) to elucidate the pros and cons of different approaches. The implications of our studies for strongly correlated systems are discussed. [1] H. Jiang, R. Gómez-Abal, P. Rinke, and M. Scheffler, Phys. Rev. Lett. 126403 (2009). [2] H. Jiang, R. Gómez-Abal, P. Rinke, and M. Scheffler, Phys. Rev. B 045108 (2010). |
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