From Atomistic Modeling to Excitation Transfer and Two-Dimensional Spectra of the FMO Light-Harvesting Complex

Carsten Olbrich, Thomas L. C. Jansen, Joerg Liebers, Mortaza Aghtar, Johan Struempfer, Klaus Schulten, Jasper Knoester, Ulrich Kleinekathoefer*, Johan Strümpfer

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

202 Citations (Scopus)
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Abstract

The experimental observation of long-lived quantum coherences in the Fenna-Matthews-Olson (FMO) light-harvesting complex at low temperatures has challenged general intuition in the field of complex molecular systems and provoked considerable theoretical effort in search of explanations. Here we report on room-temperature calculations of the excited-state dynamics in FMO using a combination of molecular dynamics simulations and electronic structure calculations. Thus we obtain trajectories for the Hamiltonian of this system which contains time-dependent vertical excitation energies of the individual bacteriochlorophyll molecules and their mutual electronic couplings. The distribution of energies and couplings is analyzed together with possible spatial correlations. It is found that in contrast to frequent assumptions the site energy distribution is non-Gaussian. In a subsequent step, averaged wave packet dynamics is used to determine the exciton dynamics in the system. Finally, with the time-dependent Hamiltonian, linear and two-dimensional spectra are determined. The thus-obtained linear absorption line shape agrees well with experimental observation and is largely determined by the non-Gaussian site energy distribution. The two-dimensional spectra are in line with what one would expect by extrapolation of the experimental observations at lower temperatures and indicate almost total loss of long-lived coherences.

Original languageEnglish
Pages (from-to)8609-8621
Number of pages13
JournalJournal of Physical Chemistry B
Volume115
Issue number26
DOIs
Publication statusPublished - 7-Jul-2011

Keywords

  • BACTERIOCHLOROPHYLL-A-PROTEIN
  • GREEN SULFUR BACTERIA
  • ENERGY-TRANSFER
  • QUANTUM COHERENCE
  • PROSTHECOCHLORIS-AESTUARII
  • MOLECULAR-DYNAMICS
  • OPTICAL-PROPERTIES
  • ANTENNA PROTEIN
  • PURPLE BACTERIA
  • SPECTROSCOPY

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