Quantum Interferences and Electron Transfer in Photosystem I

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• 作者：Nicolas Renaud ; Daniel Powell ; Mahdi Zarea ; Bijan Movaghar ; Michael R. Wasielewski ; Mark A. Ratner
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：July 25, 2013
• 年：2013
• 卷：117
• 期：29
• 页码：5899-5908
• 全文大小：520K
• 年卷期：v.117,no.29(July 25, 2013)
• ISSN：1520-5215

文摘

We have studied the electron transfer occurring in the photosystem I (PSI) reaction center from the special pair to the first iron鈥搒ulfur cluster. Electronic structure calculations performed at the DFT level were employed to determine the on-site energies of the fragments comprising PSI, as well as the charge transfer integrals between neighboring pairs. This electronic Hamiltonian was then used to compute the charge transfer dynamics, using the stochastic surrogate Hamiltonian approach to account for the coherent propagation of the electronic density but also for its energy relaxation and decoherence. These simulations give reasonable transfer time ranging from subpicoseconds to nanoseconds and predict coherent oscillations for several picoseconds. Due to these long-lasting coherences, the propagation of the electronic density can be enhanced or inhibited by quantum interferences. The impact of random fluctuations and asymmetries on these interferences is then discussed. Random fluctuations lead to a classical transport where both constructive and destructive quantum interferences are suppressed. Finally it is shown that an energy difference of 0.15 eV between the on-site energies of the phylloquinones leads to a highly efficient electron transfer even in presence of strong random fluctuations.