Iterative linearized density matrix propagation for modeling coherent excitation energy transfer in photosynthetic light harvesting
Iterative linearized density matrix propagation for modeling coherent excitation energy transfer in photosynthetic light harvesting
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DOI：
10.1063/1.3498901
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发表时间：
2010-11-14
影响因子：
4.4
通讯作者：
Coker, D. F.
中科院分区：
文献类型：
--
作者：
Huo, P.;Coker, D. F.
实验证据表明，在一些生物光捕获系统中的激发能量转移最初是相干发生的，而不是发色团之间的非相干跳跃，并且涉及相干叠加态，其中激发在相隔几纳米的多个发色团上传播。处理这种离域相干叠加态的退相干和耗散所产生的耦合到一个环境中的存在是一个重大的挑战，传统的理论工具，无论是使用微扰的方法或马尔可夫近似。本文推广了最近发展的迭代线性化密度矩阵（ILDM）传播格式[E. R. Dunkel等人，129，114106（2008）]来研究来自绿色硫细菌的Fenna-Matthews-Olsen捕光复合物模型中的相干激发能量转移。这种方法是非微扰的，并使用离散路径积分描述，采用短时间近似的密度矩阵传播子，占量子激子系统的前向和后向路径之间的干扰，同时线性化的相位之间的差异的前向和后向路径的环境自由度，从而导致在一个经典的治疗这些变量。该方法避免了马尔可夫近似，我们证明，它成功地描述了不同的发色团的网站人口的相干跳动，并给出了良好的协议与其他方法，最近已经开发的超越通常的近似，从而提供了一个新的可靠的理论工具来研究相干激子转移光捕获系统。最后，我们讨论了在独立的双线性耦合谐波发色团浴的退相干。ILDM传播方法原则上可以应用于更一般的环境描述。(C)2010年美国物理学会。[doi：10.1063/1.3498901]
Rather than incoherent hopping between chromophores, experimental evidence suggests that the excitation energy transfer in some biological light harvesting systems initially occurs coherently, and involves coherent superposition states in which excitation spreads over multiple chromophores separated by several nanometers. Treating such delocalized coherent superposition states in the presence of decoherence and dissipation arising from coupling to an environment is a significant challenge for conventional theoretical tools that either use a perturbative approach or make the Markovian approximation. In this paper, we extend the recently developed iterative linearized density matrix (ILDM) propagation scheme [E. R. Dunkel et al., J. Chem. Phys. 129, 114106 (2008)] to study coherent excitation energy transfer in a model of the Fenna-Matthews-Olsen light harvesting complex from green sulfur bacteria. This approach is nonperturbative and uses a discrete path integral description employing a short time approximation to the density matrix propagator that accounts for interference between forward and backward paths of the quantum excitonic system while linearizing the phase in the difference between the forward and backward paths of the environmental degrees of freedom resulting in a classical-like treatment of these variables. The approach avoids making the Markovian approximation and we demonstrate that it successfully describes the coherent beating of the site populations on different chromophores and gives good agreement with other methods that have been developed recently for going beyond the usual approximations, thus providing a new reliable theoretical tool to study coherent exciton transfer in light harvesting systems. We conclude with a discussion of decoherence in independent bilinearly coupled harmonic chromophore baths. The ILDM propagation approach in principle can be applied to more general descriptions of the environment. (C) 2010 American Institute of Physics. [doi:10.1063/1.3498901]