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Molecular basis of the exciton-phonon interactions in the PE545 light-harvesting complex

Posted May 6th, 2015 by sruiz
TitleMolecular basis of the exciton-phonon interactions in the PE545 light-harvesting complex
Publication TypeJournal Article
Year of Publication2014
AuthorsViani, L, Corbella M, Curutchet C, O'Reilly EJ, Olaya-Castro A, Mennucci B
JournalPhys. Chem. Chem. Phys.
Volume16
Pagination16302-16311
AbstractLong-lived quantum coherences observed in several photosynthetic pigment-protein complexes at low and at room temperatures have generated a heated debate over the impact that the coupling of electronic excitations to molecular vibrations of the relevant actors (pigments{,} proteins and solvents) has on the excitation energy transfer process. In this work{,} we use a combined MD and QM/MMPol strategy to investigate the exciton-phonon interactions in the PE545 light-harvesting complex by computing the spectral densities for each pigment and analyzing their consequences in the exciton dynamics. Insights into the origin of relevant peaks{,} as well as their differences among individual pigments{,} are provided by correlating them with normal modes obtained from a quasi-harmonic analysis of the motions sampled by the pigments in the complex. Our results indicate that both the protein and the solvent significantly modulate the intramolecular vibrations of the pigments thus playing an important role in promoting or suppressing certain exciton-phonon interactions. We also find that these low-frequency features are largely smoothed out when the spectral density is averaged over the complex{,} something difficult to avoid in experiments that underscores the need to combine theory and experiment to understand the origin of quantum coherence in photosynthetic light-harvesting.
URLhttp://dx.doi.org/10.1039/C4CP01477D
DOI10.1039/C4CP01477D