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HL: Fachverband Halbleiterphysik
HL 98: Electronic Structure Theory
HL 98.5: Vortrag
Freitag, 30. März 2012, 10:30–10:45, EW 202
Electronic and optical properties of cadmium fluoride: the role of many-body effects — •Giancarlo Cappellini1, Juergen Furthmueller2, Friedhelm Bechstedt2, and Emiliano Cadelano1 — 1SLACS-IOM-CNR and UniCA, Cagliari, Italy — 2IFTO-FSU, Jena, Germany
The electronic excitations and optical spectra of CdF2 are calculated employing state-of-the-art techniques based on density functional theory and many-body perturbation theory. We use the perturbative GW scheme proposed by Hedin for the electronic self-energy to calculate single-particle excitation properties as the energy bands and the density of states (DOS). The electronic DOS near the gap region and the energy-band structure are compared with existing data from literature. The role of many-body effects turns out to be of fundamental importance for these single-particle properties. We show moreover that also for optical properties many-body effects, treated within the Bethe-Salpeter equation framework, are crucial to allow reasonable comparison with existing experimental spectra. We discuss the existence of a bound exciton located about 1 eV below the quasiparticle gap. For both, single-particle and two-particle effects, we explore the possibility of using simplified schemes and/or approximations which could reduce the computational effort, mantaining the physical results reliable. In addition, we also present preliminary results for the fluoride BaF2 for comparison.