Hannover 2016 – scientific programme

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MO: Fachverband Molekülphysik

MO 3: Electronic Spectroscopy 1

MO 3.7: Talk

Monday, February 29, 2016, 16:00–16:15, f102

TD-DFTB analysis of time- and geometry-dependent excitonic couplings in PTCDI crystals — •Per-Arno Plötz¹, Jörg Megow², Thomas Niehaus³, and Oliver Kühn¹ — ¹Institut für Physik, Universität Rostock, Germany — ²Institut für Chemie, Universität Potsdam, Germany — ³Institut Lumière Materière, Université Claude Bernard Lyon 1, France

Polarisation effects on chromophores and their influence to the excitonic coupling are simulated for a PTCDI (perylene-tetracorboxylic-diimide) crystal [1], whose thin films are possible building blocks for optoelectronics. Starting from a classical MD trajectory Frenkel exciton parameters are calculated, i.e. the monomeric transition energies as well as the Coulomb couplings between the on-site transitions. The efficient TBFE [2] method making use of tight-binding-based density functional theory in the linear response formulation (TD-DFTB) [3] is capable not only to follow the specific inter- but also the intramolecular structural changes in a thermal environment, distinguishing it from other methods computing the Coulomb coupling with fixed transition charges. Thus the calculation of the spectral density from a classical trajectory is possible. Its analysis provides the key to assign optical properties to specific vibrational modes.
J. Megow et al., J. Phys. Chem. C, 2015, 119, 5747-5751.
P.-A. Plötz et al., J. Chem. Phys., 2014, 140, 174101.
T. A. Niehaus et al., Phys. Rev. B, 2001, 63, 085108.