Erlangen 2022 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 8: Poster 1
MO 8.19: Poster
Dienstag, 15. März 2022, 16:30–18:30, P
Excited State Dynamics of the Q-Bands in Chlorophyll a — •Lena Bäuml1, Sebastian Reiter1, Eva Sextl2, and Regina de Vivie-Riedle1 — 1Department of Chemistry, LMU Munich, Germany — 2Department of Physics, LMU Munich, Germany
During the conversion of sunlight to chemical energy via photosynthesis the pigment chlorophyll adopts different functions depending on the environment: absorption of light in the visible range, excitation energy transfer in the antenna complex, primary charge separation in the reaction centre of the photosystems and subsequent electron transfer to other redox-active cofactors. Thus, nonradiative relaxation of high-energy excited states to the lowest excited state in chlorophylls is central for the understanding of photosynthesis.
In this work, we simulate the ultrafast relaxation process in the Q-bands of chlorophyll a with grid-based wave packet quantum dynamics in several reduced-dimensional coordinate spaces. In particular we discuss the relaxation process in 2D coordinate spaces spanned by the normal modes with the highest overlap with the non-adiabatic coupling vector. The excited state energies and non-adiabatic couplings are computed at the CASPT2 level of theory to model the energy difference between the Qx and the Qy state correctly. Our results show from a purely quantum mechanical point of view how the Qx and the Qy band are strongly coupled by internal vibrations and should not be considered as isolated transitions.