Regensburg 2010 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 5: Posters: Biopolymers and Biomaterials
BP 5.5: Poster
Montag, 22. März 2010, 17:15–20:00, Poster B1
Optical properties of light-harvesting systems determined by molecular dynamics simulations — •Carsten Olbrich1, Jörg Liebers1, Michael Schreiber2, and Ulrich Kleinekathöfer1 — 1Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany — 2TU-Chemnitz, Reichenhainer Str. 70, 09126 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 [1,2]. 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. Damjanovic, I. Kosztin, U. Kleinekathöfer, and K. Schulten, Phys. Rev. E 65, 031919 (2002)
[2] L. Janosi, I. Kosztin, and A. Damjanovic, J. Chem. Phys. 125, 014903 (2006)