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BP: Fachverband Biologische Physik
BP 17: Poster II
BP 17.27: Poster
Mittwoch, 25. März 2009, 17:15–19:45, P3
Optical properties of light-harvesting systems determined by molecular dynamics simulations — •Carsten Olbrich1, Michael Schreiber2, and Ulrich Kleinekathöfer1 — 1Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany — 2Technische Universität Chemnitz, Fakultät für Naturwissenschaften, 09107 Chemnitz, Germany
Harvesting sun light to gain energy for life is initially
done by light-harvesting antenna complexes containing chlorophyll and
carotenoid molecules. Starting from the available crystal structure of
the light-harvesting systems 2 (LH2) of purple bacterium, we applied
all-atom classical molecular-dynamics (MD) simulations to the LH2 ring
embedded in a membrane. Thus obtained thermal fluctuations of the
nuclear positions provide the input for quantum chemical calculations.
To obtain the energies of the Qy excited states of the single
Bacteriochlorophyll (BChl) molecules, the semi-empirical ZINDO/CIS method
is used to be able to analyze longer time series as was previously
possible with the CIS method [1]. To include solvent
effects to the excited state dynamics, the surrounding atoms of the BChls
are treated as classical point charges in the QM calculations. Using the
nuclear motion and the obtained energy differences between ground and
Qy excited states with a time-dependent Hamiltonian, we are able to
calculate optical properties of the analyzed system.
[1] A. Damjanović, I. Kosztin, U. Kleinekathöfer and K. Schulten, Phys. Rev. E 65, 031919 (2002).