A theoretical investigation into the effects of temperature on spatiotemporal dynamics of EET in the FMO complex.
A theoretical investigation into the effects of temperature on spatiotemporal dynamics of EET in the FMO complex.
复制标题
DOI：
10.1021/jp509103e
复制
发表时间：
2015-03
期刊：
影响因子：
--
通讯作者：
Colm G. Gillis;G. Jones
中科院分区：
文献类型：
--
作者：
Colm G. Gillis;G. Jones
方法中，人口动态演化的激子的基础和时空运动的激发随后获得的投影到网站的基础。系统本征态的波动明确包括通过振动的发色团，这是参数化的从头计算。两个极限情况下的动力学被认为是，即，非相干制度，其中状态人口对应于合奏的经典朗道-齐纳（LZ）轨迹，和相干制度，其中的密度矩阵传播的量子刘维尔方程（QLE）。对于QLE模拟，群体动力学表明，细菌叶绿素a1和a2有效地作为一个单一的单位在77 K，但作为独立的发色团在300 K。在生理温度下，较低能量激子态的群体跳动相当慢，从而有助于转移到汇。从LZ轨迹的结果表明，在经典的图片，较高的温度导致激子到达汇的概率较低。激子光谱在高温下的加宽改变了激子在LZ形式主义中的路径，也增加了捕获的可能性。这项研究支持这样的观点，即一个连贯的机制可能有助于EET在生理温度下，因为在中间能量网站的激发陷阱被阻止。此外，离域振动（即，独立振荡器的叠加）被发现有助于在短时间内的能量转移。
Methodologies are presented in which population dynamics are evolved in the exciton basis and spatiotemporal movement of excitations is subsequently obtained by projection to the site basis. Fluctuations of system eigenstates are explicitly included through vibrations of the chromophores, which are parametrized by ab initio calculations. Two limiting cases of dynamics are considered, namely, the incoherent regime, where state populations correspond to ensembles of classical Landau-Zener (LZ) trajectories, and the coherent regime, where the density matrix is propagated by the quantum Liouville equation (QLE). For QLE simulations, population dynamics show that bacteriochlorophyll a1 and a2 effectively act as a single unit at 77 K but as independent chromophores at 300 K. Population beatings for the lower energy exciton states are considerably slower at physiological temperatures, thus assisting transfer to the sink. Results from LZ trajectories indicate that, within the classical picture, higher temperatures result in a lower probability of the exciton reaching the sink. A broadening of the excitonic spectrum at high temperature alters the pathways of the excitons in the LZ formalism and also increases the possibility of trapping. This study supports the view that a coherent mechanism may assist EET at physiological temperatures since the trapping of excitations in intermediate energy sites is prevented. Furthermore, delocalized vibrations (i.e., superpositions of independent oscillators) are found to assist energy transfer at short times.