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arXiv · 2311.02024

Absorption spectra of the purple nonsulfur bacteria light-harvesting complex: a DFT study of the B800 part

L. V. Begunovich·E. A. Kovaleva·M. M. Korshunov·V. F. Shabanov
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Abstract

We've studied the B800 part of Rhodoblastus acidophilus light-harvesting complex (LH2) by several quantum chemical techniques based on the density functional theory (DFT) and determined the specific method and a minimal reliable model suitable for further studies of the LH2. In addition to bacteriochlorophyll a molecules, the minimal model includes two $\alpha$ and one $\beta$ chain amino acids. Within the model, we are able to reproduce the contribution of the B800 ring of nine bacteriochlorophyll a molecules to the near infrared $Q_y$ absorption band. We also discuss the use of hybrid DFT calculations for precise energy and optical estimations and DFT-based tight binding (DFTB) method for the large-scale calculations. Crucial importance of Hartree-Fock exchange interaction for the correct description of B800 peak position was shown.

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L. V. Begunovich, E. A. Kovaleva, M. M. Korshunov, V. F. Shabanov. 2023-11-03. Absorption spectra of the purple nonsulfur bacteria light-harvesting complex: a DFT study of the B800 part. https://doi.org/10.1016/j.jphotochem.2023.115454

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