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Title: Ab initio molecular orbital calculations of electronic couplings in the LH2 bacterial light-harvesting complex of Rps. acidophila

Abstract

The results of ab initio molecular orbital calculations of excited states and electronic couplings (for energy transfer) between the B800 and B850 bacteriochlorophyll a (Bchl) chromophores in the peripheral light-harvesting complex (LH2) of the purple photosynthetic bacterium Rhodopseudomonas acidophila are reported. Electronic couplings are estimated from supermolecule calculations of Bchl dimers using the Ci-singles methodology and 3-21G{sup *} or 6-31G{sup *} basis sets. A scheme for dissecting the coupling into contributions from the Coulombic coupling and the short-range coupling (i.e., dependent on interchromophore orbital overlap) is reported. B850 couplings are calculated to be [total (Coulombic + short)]: intrapolypeptide dimer 320 (265 + 55) cm{sup {minus}1} and interpolypeptide dimer 255 (195 + 60) cm{sup {minus}1} at the CIS/6-31G{sup *} level. These results differ significantly from those estimated using the point dipole approximation. The effect of including Mg ligands (His residues) and H-bonding residues (Trp and Tyr) is also investigated. The consequences for superradiance and energy transfer dynamics and mechanism are discussed.

Authors:
;  [1];  [2];  [3]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Chemistry
  2. Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Chemistry
  3. Univ. of Glasgow (United Kingdom). Div. of Biochemistry and Molecular Biology
Publication Date:
OSTI Identifier:
345118
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
Additional Journal Information:
Journal Volume: 103; Journal Issue: 13; Other Information: PBD: 1 Apr 1999
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; ELECTRONIC STRUCTURE; PHOTOSYNTHESIS; PHOTOSYNTHETIC BACTERIA; QUANTUM MECHANICS; MOLECULAR ORBITAL METHOD; EXCITED STATES; ENERGY TRANSFER

Citation Formats

Scholes, G D, Fleming, G R, Lawrence Berkeley National Lab., CA, Gould, I R, and Cogdell, R J. Ab initio molecular orbital calculations of electronic couplings in the LH2 bacterial light-harvesting complex of Rps. acidophila. United States: N. p., 1999. Web. doi:10.1021/jp9839753.
Scholes, G D, Fleming, G R, Lawrence Berkeley National Lab., CA, Gould, I R, & Cogdell, R J. Ab initio molecular orbital calculations of electronic couplings in the LH2 bacterial light-harvesting complex of Rps. acidophila. United States. doi:10.1021/jp9839753.
Scholes, G D, Fleming, G R, Lawrence Berkeley National Lab., CA, Gould, I R, and Cogdell, R J. Thu . "Ab initio molecular orbital calculations of electronic couplings in the LH2 bacterial light-harvesting complex of Rps. acidophila". United States. doi:10.1021/jp9839753.
@article{osti_345118,
title = {Ab initio molecular orbital calculations of electronic couplings in the LH2 bacterial light-harvesting complex of Rps. acidophila},
author = {Scholes, G D and Fleming, G R and Lawrence Berkeley National Lab., CA and Gould, I R and Cogdell, R J},
abstractNote = {The results of ab initio molecular orbital calculations of excited states and electronic couplings (for energy transfer) between the B800 and B850 bacteriochlorophyll a (Bchl) chromophores in the peripheral light-harvesting complex (LH2) of the purple photosynthetic bacterium Rhodopseudomonas acidophila are reported. Electronic couplings are estimated from supermolecule calculations of Bchl dimers using the Ci-singles methodology and 3-21G{sup *} or 6-31G{sup *} basis sets. A scheme for dissecting the coupling into contributions from the Coulombic coupling and the short-range coupling (i.e., dependent on interchromophore orbital overlap) is reported. B850 couplings are calculated to be [total (Coulombic + short)]: intrapolypeptide dimer 320 (265 + 55) cm{sup {minus}1} and interpolypeptide dimer 255 (195 + 60) cm{sup {minus}1} at the CIS/6-31G{sup *} level. These results differ significantly from those estimated using the point dipole approximation. The effect of including Mg ligands (His residues) and H-bonding residues (Trp and Tyr) is also investigated. The consequences for superradiance and energy transfer dynamics and mechanism are discussed.},
doi = {10.1021/jp9839753},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
number = 13,
volume = 103,
place = {United States},
year = {1999},
month = {4}
}