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Title: Excited states of the bacteriochlorophyll b dimer of rhodopseudomonas viridis. A QM/MM study of the photosynthetic reaction center that includes MM polarization

Abstract

We present a hybrid quantum mechanical/molecular mechanical (QM/MM) model for microscopic solvation effects that includes polarizability in the MM region (QM/MMpol). QM/MMpol treatment of both ground and excited states is presented in the formalism. We present QM/MMpol analysis of the ground and electronic excited states of the bacteriochlorophyll b dimer (P) of the photosynthetic reaction center (RC) of Rhodopseudomonas viridis using the INDO/S method. The static-charge potential from the MM model of the RC alone causes Q{sub y1} to have significantly better agreement with the Stark effect results than isolated P. However, consideration of the protein polarization potential is further required to obtain more complete agreement with Stark effect experiments. Thus, we calculate a Q{sub y1} transition energy at 10826 cm{sup -1} with a ground to excited state change in dipole moment of 4.8 D; an absorption Stark effect angle of 43{degree}; a net shift of 0.15 electrons from the L subunit to the M subunit of P; and a linear dichroism angle (between the transition moment of Q{sub y1} and the pseudo-C{sub 2} axis of the RC) of 81{degree}. These results are in good agreement with experiment. Interestingly, we find that net CT increase is greater for Q{sub y1}more » than for the second excited state of P (Q{sub y2}), a result that we anticipated in an early model dimer study. 77 refs., 3 figs., 2 tabs.« less

Authors:
;  [1]
  1. Pacific Northwest Lab., Richland, WA (United States)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
50500
DOE Contract Number:  
AC06-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry
Additional Journal Information:
Journal Volume: 99; Journal Issue: 17; Other Information: PBD: 27 Apr 1995
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 55 BIOLOGY AND MEDICINE, BASIC STUDIES; 99 MATHEMATICS, COMPUTERS, INFORMATION SCIENCE, MANAGEMENT, LAW, MISCELLANEOUS; CHLOROPHYLL; EXCITED STATES; CHARGE TRANSPORT; PHOTOSYNTHETIC REACTION CENTERS; DIMERS; BACTERIA; SOLAR ENERGY CONVERSION; QUANTUM MECHANICS; MOLECULAR MODELS; GROUND STATES; MATHEMATICAL MODELS; MOLECULAR ORBITAL METHOD; STARK EFFECT; ELECTRON TRANSFER; CALCULATION METHODS; SPECTRAL SHIFT; HAMILTONIANS; POLARIZATION

Citation Formats

Thompson, M A, and Schenter, G K. Excited states of the bacteriochlorophyll b dimer of rhodopseudomonas viridis. A QM/MM study of the photosynthetic reaction center that includes MM polarization. United States: N. p., 1995. Web. doi:10.1021/j100017a017.
Thompson, M A, & Schenter, G K. Excited states of the bacteriochlorophyll b dimer of rhodopseudomonas viridis. A QM/MM study of the photosynthetic reaction center that includes MM polarization. United States. https://doi.org/10.1021/j100017a017
Thompson, M A, and Schenter, G K. 1995. "Excited states of the bacteriochlorophyll b dimer of rhodopseudomonas viridis. A QM/MM study of the photosynthetic reaction center that includes MM polarization". United States. https://doi.org/10.1021/j100017a017.
@article{osti_50500,
title = {Excited states of the bacteriochlorophyll b dimer of rhodopseudomonas viridis. A QM/MM study of the photosynthetic reaction center that includes MM polarization},
author = {Thompson, M A and Schenter, G K},
abstractNote = {We present a hybrid quantum mechanical/molecular mechanical (QM/MM) model for microscopic solvation effects that includes polarizability in the MM region (QM/MMpol). QM/MMpol treatment of both ground and excited states is presented in the formalism. We present QM/MMpol analysis of the ground and electronic excited states of the bacteriochlorophyll b dimer (P) of the photosynthetic reaction center (RC) of Rhodopseudomonas viridis using the INDO/S method. The static-charge potential from the MM model of the RC alone causes Q{sub y1} to have significantly better agreement with the Stark effect results than isolated P. However, consideration of the protein polarization potential is further required to obtain more complete agreement with Stark effect experiments. Thus, we calculate a Q{sub y1} transition energy at 10826 cm{sup -1} with a ground to excited state change in dipole moment of 4.8 D; an absorption Stark effect angle of 43{degree}; a net shift of 0.15 electrons from the L subunit to the M subunit of P; and a linear dichroism angle (between the transition moment of Q{sub y1} and the pseudo-C{sub 2} axis of the RC) of 81{degree}. These results are in good agreement with experiment. Interestingly, we find that net CT increase is greater for Q{sub y1} than for the second excited state of P (Q{sub y2}), a result that we anticipated in an early model dimer study. 77 refs., 3 figs., 2 tabs.},
doi = {10.1021/j100017a017},
url = {https://www.osti.gov/biblio/50500}, journal = {Journal of Physical Chemistry},
number = 17,
volume = 99,
place = {United States},
year = {1995},
month = {4}
}