Berlin 2015 – wissenschaftliches Programm
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SYME: Symposium Frontiers of Electronic Structure Theory: Many-body Effects on the Nano-Scale
SYME 6: Frontiers of Electronic Structure Theory: Many-Body Effects on the Nano-Scale V
SYME 6.6: Vortrag
Donnerstag, 19. März 2015, 12:00–12:15, MA 004
Starting-point dependence in the Bethe-Salpeter equation: example of rutile TiO2 — •Olga Turkina, Ute Werner, Dmitrii Nabok, and Claudia Draxl — Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Zum Großen Windkanal 6, D-12489 Berlin, Germany
Many-body perturbation theory, combining the GW approach and the Bethe-Salpeter equation (BSE), is a powerful tool for the description of one- and two-particle excitations. However, employing density functional theory as a starting point for these methods may lead to results that depend on the choice of the exchange-correlation (xc) functional. This starting-point dependence is well known for the G0W0 approximation. Such dependence is expected to occur also for BSE calculations, however, has not yet been investigated. With the example of rutile TiO2, we show that this is, indeed, the case. We employ two different xc functionals: the generalized gradient approximation (PBE) and a hybrid functional (PBE0’), combining a fraction of 25% exact exchange with PBE. The electronic structure is calculated using the G0W0 approximation. The BSE is solved to obtain the optical absorption spectra. These are analyzed with regard to the influence of eigenvalues, wave functions, and screening as originating from different xc functionals.