Criteria for quantum coherent transfer of excitations between chromophores in a polar solvent

Gilmore, Joel; McKenzie, Ross H.

doi:10.1016/j.cplett.2005.12.104

Cited by 44 publications

(91 citation statements)

References 43 publications

(54 reference statements)

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“…1(a), the PIMC calculations coincide with the result of Eq. (9). A moderate increase of the coupling (α = 1/10), Fig.…”

Section: Dimers With Trapsmentioning

confidence: 99%

“…By assuming not too strong couplings to the environment and a single initial excitation of one of the TLS, one can map the two TLS onto a single TLS, if, without the trap, the probability of finding the excitation in the system is conserved [9]. We note that various systems with, e.g., radial symmetry and a trap in the center can effectively be mapped onto the dimer if initially the excitation is homogeneously distributed over the periphery [10].…”

Section: Introductionmentioning

confidence: 99%

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Dissipative dynamics with trapping in dimers

et al. 2010

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The trapping of excitations in systems coupled to an environment allows to study the quantum to classical crossover by different means. We show how to combine the phenomenological description by a nonhermitian Liouville-von Neumann Equation (LvNE) approach with the numerically exact path integral MonteCarlo (PIMC) method, and exemplify our results for a system of two coupled two-level systems. By varying the strength of the coupling to the environment we are able to estimate the parameter range in which the LvNE approach yields satisfactory results. Moreover, by matching the PIMC results with the LvNE calculations we have a powerful tool to extrapolate the numerically exact PIMC method to long times.

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“…1(a), the PIMC calculations coincide with the result of Eq. (9). A moderate increase of the coupling (α = 1/10), Fig.…”

Section: Dimers With Trapsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dissipative dynamics with trapping in dimers

et al. 2010

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“…For each model we derive an expression for the spectral density (5). This allows us to explore how the relative importance of the dielectric relaxation of the solvent, bound water, and protein depends on the relevant length scales (the relative size of the chromophore, the protein and the thickness of the layer of bound water) and time scales (the dielectric relaxation times of the protein, bound water and the solvent) as is discussed in Section V. Many experimentally obtained spectral densities can be fitted to a sum of Lorentzians (see Table II).…”

Section: Overview Of the Papermentioning

confidence: 99%

“…For biomolecular systems, the spin-boson model has previously been applied to electron transfer. [3,40,41] We have recently shown the relevance of the spin-boson model to understanding the effect of the environment on Förster resonant energy transfer between two chromophores [5]. Of particular interest is the case where two molecules are coupled by Resonance Energy Transfer (RET), such as rings of chlorophyll molecules in photosynthesis and in Fluorescent Resonance Energy Transfer spectroscopy (FRET).…”

Section: Introductionmentioning

confidence: 99%

“…In most cases the change in quantum state associated with the functional event (e.g., transition to an excited electronic state) is associated with a change in the electric dipole moment of the subsystem. Since the protein contains polar residues and is surrounded by a highly polar solvent (water) [5,6,7,8] there is a strong interaction between the functional subsystem and its environment. Consequently, the environment can have a significant effect on the quantum dynamics of the subsystem.…”

Section: Introductionmentioning

confidence: 99%

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Quantum Dynamics of Electronic Excitations in Biomolecular Chromophores: Role of the Protein Environment and Solvent

2008

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We consider continuum dielectric models as minimal models to understand the effect of a surrounding globular protein and solvent on the quantum dynamics of electronic excitations in a biological chromophore. For these models we derive expressions for the frequency dependent spectral density which describes the coupling of the electronic levels in the chromophore to its environment. The magnitude and frequency dependence of the spectral density determines whether or not the quantum dynamics is coherent or incoherent, and thus whether on not one can observe quantum interference effects such as Rabi oscillations. We find the contributions to the spectral density from each component of the chromophore environment: the bulk solvent, protein, and water bound to the protein. The relative importance of each component to the quantum dynamics of the chromophore is determined by the time scale on which one is considering the dynamics. Our results provide a natural explanation and model for the different time scales observed in the spectral density extracted from the solvation dynamics probed by ultra-fast laser spectroscopy techniques such as the dynamic Stokes shift and three pulse photon echo spectroscopy. Our results are used to define under what conditions the dynamics of the excited chromophore is dominated by the surrounding protein and when it is dominated by dielectric fluctuations in the solvent. We show that even when the chromophore is shielded from the solvent by the protein ultra-fast solvation can be dominated by the solvent. Hence, we suggest that the ultra-fast solvation recently seen in some biological chromophores should not necessarily be assigned to ultra-fast protein dynamics. The magnitudes of the spectral density that we estimate from our continuum models and extracted from experiment suggest that most quantum dynamics of electronic excitations is incoherent. A possible exception is transfer of excitons between neigbouring chromophores in photosynthetic systems.

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Emergence of molecular chirality due to chiral interactions in a biological environment

2014

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We explore the interplay between tunneling process and chiral interactions in the discrimination of chiral states for an ensemble of molecules in a biological environment. Each molecule is described by an asymmetric double-well potential and the environment is modeled as a bath of harmonic oscillators. We carefully analyze different time-scales appearing in the resulting master equation at both weak-and strong-coupling limits. The corresponding results are accompanied by a set of coupled differential equations characterizing optical activity of the molecules. We show that, at the weak-coupling limit, chiral interactions prohibit the coherent racemization induced by decoherence effects and thus preserve the initial chiral state. At the strong-coupling limit, considering the memory effects of the environment, Markovian behavior is observed at long times.

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Criteria for quantum coherent transfer of excitations between chromophores in a polar solvent

Cited by 44 publications

References 43 publications

Dissipative dynamics with trapping in dimers

Dissipative dynamics with trapping in dimers

Quantum Dynamics of Electronic Excitations in Biomolecular Chromophores: Role of the Protein Environment and Solvent

Emergence of molecular chirality due to chiral interactions in a biological environment

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