Mainz 2017 – scientific programme

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MO: Fachverband Molekülphysik

MO 11: Molecular Nanostructures and Solids

MO 11.2: Talk

Wednesday, March 8, 2017, 14:45–15:00, N 25

Thermal Fluctuations of Frenkel Exciton Hamiltonian — •Per-Arno Plötz¹, Jörg Megow², Thomas Niehaus³, and Oliver Kühn¹ — ¹Institut für Physik, Universität Rostock, Germany — ²Institut für Chemie, Universität Potsdam, Germany — ³Institute Lumière Matière, Université Lyon 1, France

Effects of thermal fluctuations on the electronic excitation energies and intermonomeric Coulomb couplings are investigated via density functional theory based tight binding in the linear response formulation (TD-DFTB) and ground state classical molecular dynamics. As a result, a parametrised Frenkel exciton Hamiltonian is obtained, with the effect of exciton-vibrational coupling being described by spectral densities. Employing dynamically defined normal modes, these spectral densities are analysed in great detail, thus providing insight into the effect of specific intramolecular motions on excitation energies and Coulomb couplings. First application is a PTCDI crystal where results based on force field trajectories are compared to DFTB driven trajectories. Further application is applied in combination with a QM/MM approach on a BChla dimer in solution.