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

doi:10.1016/j.jphotochem.2023.115454

paper

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

arXiv:2311.02024 · doi:10.1016/j.jphotochem.2023.115454

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 $α$ and one $β$ 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.

11 pages + supplementary materials (2 pages)