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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: Molecular Electronics and Excited State Properties I
CPP 13.2: Talk
Monday, March 17, 2025, 17:30–17:45, H38
Theoretical perspectives on ground- and excited state absorption in organic materials: comparing TDDFT, GW/BSE, and post-Hartree-Fock methods — •Narges Taghizade1, Andreas Windischbacher1, Andreas W. Hauser2, and Peter Puschnig1 — 1Institute of Physics, University of Graz, Austria — 2Institute of Experimental Physics, Graz University of Technology, Austria
Ground- and excited-state absorption (ESA) properties of conjugated organic materials are fundamental to the development of advanced optoelectronic devices. In this contribution, we specifically focus on molecules, which pose challenges to traditional theoretical approaches owing to significant electron correlation resulting in complex charge transfer and multi-reference characteristics, particularly when it comes to excited state properties. To address these complexities, we compute the ground and ESA spectra using a number of complementary, advanced theoretical methods. First, we employ time-dependent density functional theory within the linear and quadratic response frameworks, respectively. Second, we present results from a GW/BSE many-body perturbation theory approach thereby addressing the challenge of accurately accounting for charge transfer excitations. Third, we also apply post-Hartree-Fock methods, such as the multi-configurational self-consistent field method in order to tackle the strong electron correlation and multi-reference effects. The comparison of our results highlights the strengths and limitations of various computational approaches and offers a pathway toward improved theoretical models for the design of efficient optoelectronic materials.
Keywords: ground and excited state absorption; pi-conjugated molecules; time-dependent density functional theory; many-body perturbation theory; post-Hartree-Fock methods