Dr. Sebastian Reiter
Department of Chemistry, Ludwig-Maximilians-Universität München
spricht zum Thema
Multiscale Modelling of Light-Harvesting in Photosystem I: The Impact of Natural and Artificial Environments
Photosystem I (PS I) is one of the most efficient light-harvesting systems in nature. Its antenna complex of chlorophylls absorbs solar energy and transfers it to a reaction center, where the energy is used to drive one of the fundamental redox processes of photosynthesis. Understanding the high efficiency of his process requires an accurate evaluation of the chlorophyll absorption energies, affected by their natural environment (site energies), as well as the excitonic coupling between the pigments. Moreover, the molecular dynamics at physiological temperatures may be of relevance. However, this task poses a challenge to computational studies due to the large scale and complexity of the system.
Here we present a fully atomistic and dynamic computational model of cyanobacterial (T. elongatus) PS I [1]. In particular, the trimeric PS I complex is embedded in a solvated lipid membrane to describe the natural environment of the chlorophyll network as thoroughly as possible. With this structural model, geometries are sampled from classical trajectories and site energies are calculated for each chlorophyll with the high-level DFT/MRCI method in a QM/MM framework. This approach allows to obtain accurate site energies and excitonic couplings under explicit consideration of electrostatic interactions with the natural environment. Our results identify transient energy traps and barriers in the antenna complex and reveal a fundamental asymmetry in the reaction center. Going beyond an understanding of the purely natural light-harvesting process to potential applications in artificial photosynthetic devices, PS I may be embedded in a metal organic framework (MOF) [2], capable of protecting the photosystem against adverse environmental conditions. In this context, the model is extended to include the MOF and perform molecular dynamics simulations for the bio-nanohybrid system. With the help of QM/MM calculations, we analyze the impact of the strongly interacting environment on the structure and function of PS I and discuss possible implications for future devices.
[1] S. Reiter, F. Kiss, J. Hauer, R. de Vivie-Riedle, Chem. Sci. 2023, 14, 3117–3131.
DOI: 10.1039/D2SC06160K
[2] S. Reiter, I. Gordiy, K. L. Kollmannsberger, F. Liu, E. Thyrhaug, D. Leister,
J. Warnan, J. Hauer, R. de Vivie-Riedle, Phys. Chem. Chem. Phys. 2024, 26,
23228–23239. DOI: 10.1039/D4CP03021D
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