Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 84: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles VI (jointly with TT)
O 84.5: Vortrag
Freitag, 30. März 2012, 11:45–12:00, HE 101
(contribution withdrawn)Accounting for dynamical screening in optical absorption spectra — •Lorenzo Sponza1,2, Matteo Guzzo1,2, Christine Giorgetti1,2, and Lucia Reining1,2 — 1LSI-Ecole Polytechnique, Palaiseau, France — 2ETSF : European Theoretical Spectroscopy Facility
In optics, absorption spectra are computed via the evaluation of the two particle correlation function L of the material which is given by the differentiation of the single particle Green-s function G1 with respect to an external (perturbing) potential U. State of the art calculations of optical absorption spectra rely on the Bethe-Salpeter Equation (BSE) and they make use of static screening W. Though, the inclusion of dynamical effects at a BSE level is a subject of both theoretical and technological interest. As an example, in some photovoltaic cells multiple-exciton generation (MEG)[2] has been proposed to improve drastically the efficiency of the device but to describe absorption in the presence of MEG one has to account for the dynamical screening.
Recently G1 has been derived as exact solution of a differential functional equation which allows the excplicit treatment of W(ω) [1]. Inspired by this work, we extended its strategy to the case of absorption, that is to the computation of L. We found a non-linear integro-differential equation that can be solved through some careful approximation. In this work we present an analysis of the solution of the problem and a comparison with standard Bethe-Salpeter approach.
[1] M.Guzzo et al., Phys. Rev. Lett. 107, 166401 (2011) [2] for MEG see for example Kheifets et al., Phys. Rev. B 68, 233205 (2003)