Dresden 2020 – scientific programme
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DS: Fachverband Dünne Schichten
DS 23: Frontiers in Electronic-Structure Theory - Focus on Electron-Phonon Interactions III (joint session O/CPP/DS/HL)
DS 23.5: Talk
Wednesday, March 18, 2020, 11:45–12:00, GER 38
Polarons in extended p-conjugated systems: the role of electron correlation. — •Daniele Fazzi1, Klaus Meerholz1, and Fabrizia Negri2 — 1Institut für Physikalische Chemie, Universität zu Köln, Luxemburger str. 116, 50939 Köln, Germany — 2Dipartimento di Chimica, Università di Bologna, via F. Selmi, 2, 40126 Bologna, Italy
Polarons play a crucial role in governing charge transfer in organic materials. An accurate description of their electronic structure and electron-phonon couplings is mandatory to understand their response and transport properties.
We report a comprehensive investigation of polarons in extended p-conjugated systems (ladder-type polymers, graphene nano-ribbons, and cyanine-based compounds [1-2]). We show how spin polarized DFT lead to solutions of the polarons wavefunction which are not the most stable ones. This aspect, can be traced back to the multireference character of polarons. Broken symmetry DFT can address the electronic and structural properties of polarons, providing a correct assessment of charge transport parameters, otherwise incorrectly computed [3]. Multi-reference wavefunction methods are also considered to take into account correlation effects in charged and excited states.
Our study calls for a careful assessment in the description of charged/excited states in conjugated materials.
[1] Wang, S., et al., Adv. Mater. 2018, 30, 1801898. [2] Medina, S. et al., Phys. Chem. Chem. Phys., 2019, 21, 7281-7288. [3] Fazzi, D. et al, J. Mat. Chem. C., 2019, 7, 12876-12885.