Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 66: Focus Session: Frontiers of Electronic Structure Theory - Non-Equilibrium Phenomena at the Nano-Scale IV (organized by O)
TT 66.9: Vortrag
Mittwoch, 2. April 2014, 12:45–13:00, TRE Ma
The electronic structure of quinacridone: Optimally tuned range-separated hybrid functional versus GW results — Daniel Lüftner1, Sivan Refaely-Abramson2, Michael Pachler1, Michael G. Ramsey1, Leeor Kronik2, and •Peter Puschnig1 — 1Institut für Physik, Karl-Franzens-Universität Graz, Austria — 2Department of Materials and Interfaces, Weizmann Institute of Science, Israel
Quinacridone is an organic molecule (C20H12N2O2) utilized in the formation of organic pigments. It has also been discussed for usage in organic electronics particularly due to its stability under ambient conditions and its tendency to form self-assembled supramolecular networks. Here, we report on its electronic structure, both, for the isolated molecule as well as for the alpha- and beta- bulk molecular crystal polymorphs. We employ an optimally tuned range-separated hybrid functional (OT-RSH) within density functional theory as well as GW corrections within a many-body perturbation theory framework. A comparison of the theoretical results obtained with the different levels of theory and a subsequent comparison with experimental data from angle-resolved photoemission spectroscopy emphasize the need for going beyond simple semi-local DFT-functionals in order to obtain the correct orbital ordering. Furthermore the comparison indicates that the results obtained with OT-RSH greatly improve those of standard DFT functionals and achieve an agreement with experiment at the level of GW calculations, thus making the OT-RSH an alternative to the computationally more expensive GW approach.