Exciton Delocalization in the B850 Light-Harvesting Complex:  Comparison of Different Measures

Dahlbom, Mats; Pullerits, Tõnu; Mukamel, Shaul; Sundström, Villy

doi:10.1021/jp004496i

Cited by 116 publications

(172 citation statements)

References 56 publications

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“…This limitation has been addressed by Kühn & Sundström [53], and by Mukamel [22,36,54,55]. Kühn & Sundström sought to plot a distribution of the inter-site coherences, based on the separation between the sites:…”

Section: (B) Exciton Wavepacket Measuresmentioning

confidence: 99%

Measures and implications of electronic coherence in photosynthetic light-harvesting

Smyth

Fassioli

Scholes

2012

Phil. Trans. R. Soc. A.

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We review various methods for measuring delocalization in light-harvesting complexes. Direct relations between inverse participation ratios (IPRs) and entanglement measures are derived. The B850 ring from the LH2 complex in Rhodopseudomonas acidophila is studied. By analysing electronic energy transfer dynamics in the B850 ring using different metrics for quantifying excitonic delocalization, we conclude that measures of entanglement are far more robust (in terms of time scale, temperature and level of decoherence) than IPRs, and are therefore more appropriate for the purpose of studying the time evolution of coherence in a system.

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Section: (B) Exciton Wavepacket Measuresmentioning

confidence: 99%

Measures and implications of electronic coherence in photosynthetic light-harvesting

Smyth

Fassioli

Scholes

2012

Phil. Trans. R. Soc. A.

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“…Because the correlation function averages wave functions that are localized on different segments of the chain, it is a suitable measure to obtain statistical information on the type of exciton states that dominate at a certain energy and of their localization lengths. Other measures used to describe exciton localization, such as the inverse participation ratio calculated from different distributions, 37,38 or the absolute value correlation function do not provide such information. The correlation function for = 0.2J is shown in Fig.…”

Section: ͑12͒mentioning

confidence: 99%

Localization and coherent dynamics of excitons in the two-dimensional optical spectrum of molecular J-aggregates

Dijkstra¹,

Jansen²,

Knoester³

2008

The Journal of Chemical Physics

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Two-dimensional optical spectra of J-aggregates at low temperature provide a large amount of information about the nature and dynamics of exciton states that is hidden in conventional broad band pump-probe spectra. By using numerical simulations, we study the two-dimensional absorption spectrum and find that it is dominated by a V-shaped negative peak and a blueshifted elliptic positive peak. We demonstrate a simple method to derive the energy dependence of the exciton localization size from the distance between these two features in the zero waiting time experiment. When the waiting time is turned on, the V peak is filled with an extra positive peak resulting from population relaxation. From the time evolution of this peak, energy dependent relaxation rates can be obtained. The oscillations of coherent contributions to the two-dimensional spectrum are not damped by inhomogeneous mechanisms and can be seen clearly.

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“…An extensive comparison of many different measures for the coherence length has been presented for LH2 in the presence of static disorder. 20 Others have used direct comparisons of the wavefunctions or the density matrices in order to develop a qualitative understanding of how disorder leads to localization. 8,17,21,22 The effects of the particular choice of the distribution of static disorder on the coherence length as well as the role of diagonal and off-diagonal disorder in one-dimensional chains and in extended tubular aggregate systems have also been explored.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium-reduced density matrix formulation: Influence of noise, disorder, and temperature on localization in excitonic systems

2012

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An exact method to compute the entire equilibrium reduced density matrix for systems characterized by a system-bath Hamiltonian is presented. The approach is based upon a stochastic unraveling of the influence functional that appears in the imaginary time path integral formalism of quantum statistical mechanics. This method is then applied to study the effects of thermal noise, static disorder, and temperature on the coherence length in excitonic systems. As representative examples of biased and unbiased systems, attention is focused on the well-characterized light harvesting complexes of FMO and LH2, respectively. Due to the bias, FMO is completely localized in the site basis at low temperatures, whereas LH2 is completely delocalized. In the latter, the presence of static disorder leads to a plateau in the coherence length at low temperature that becomes increasingly pronounced with increasing strength of the disorder. The introduction of noise, however, precludes this effect. In biased systems, it is shown that the environment may increase the coherence length, but only decrease that of unbiased systems. Finally it is emphasized that for typical values of the environmental parameters in light harvesting systems, the system and bath are entangled at equilibrium in the single excitation manifold. That is, the density matrix cannot be described as a product state as is often assumed, even at room temperature. The reduced density matrix of LH2 is shown to be in precise agreement with the steady state limit of previous exact quantum dynamics calculations. * Electronic address: jianshu@mit.edu 2

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Exciton Delocalization in the B850 Light-Harvesting Complex: Comparison of Different Measures

Cited by 116 publications

References 56 publications

Measures and implications of electronic coherence in photosynthetic light-harvesting

Measures and implications of electronic coherence in photosynthetic light-harvesting

Localization and coherent dynamics of excitons in the two-dimensional optical spectrum of molecular J-aggregates

Equilibrium-reduced density matrix formulation: Influence of noise, disorder, and temperature on localization in excitonic systems

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