Regensburg 2010 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 12: Poster: Electronic and Optical Properties of Organic Systems

CPP 12.9: Poster

Monday, March 22, 2010, 16:30–18:00, Poster C

Exciton transfer in light-harvesting systems — •Jörg Liebers, Carsten Olbrich, and Ulrich Kleinekathöfer — Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany

The exciton dynamics in the light-harvesting 2 system (LH2) of purple bacterium are studied with a quantum-classical approach that combines molecular dynamics simulations (MD) with quantum chemistry calculations and quantum dynamical simulations. To obtain the thermal fluctuations of the nuclear positions of the LH2 ring embedded in a membrane, all-atom classical MD simulations were performed. The results of these simulations serve as an input for quantum chemical calculations to determine the energies of the Q_y excited states of the single Bacteriochlorophyll (BChl) molecules. From the results of these calculations we construct a time-dependent Hamiltonian of the LH2 exciton system and the spectral density which describes the interaction of the BChl system and the environment. The exciton dynamics are simulated using two different formalisms. A density matrix approach using the spectral density [1,2] and wave packet dynamics based on the time-dependent Hamiltonian. To compare our approach to experimental results, optical spectra of the LH2 complex are calculated.

[1] U. Kleinekathöfer, J. Chem. Phys. 121, 2505 (2004).

[2] U. Kleinekathöfer, I. Barvik, P. Herman, I. Kondov and

 M. Schreiber, J. Phys. Chem. B 107, 14 094-14 102 (2003).