An Ab Initio Description of the Excitonic Properties of LH2 and Their Temperature Dependence
An Ab Initio Description of the Excitonic Properties of LH2 and Their Temperature Dependence
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DOI：
10.1021/acs.jpcb.6b06585
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发表时间：
2016-11-10
影响因子：
3.3
通讯作者：
Mennucci, Benedetta
中科院分区：
文献类型：
--
作者：
Cupellini, Lorenzo;Jurinovich, Sandro;Mennucci, Benedetta
光合生物中光捕获（LH）天线的光谱特性代表了每种特定色素蛋白复合物所独有的指纹。因此，光谱观测通常与 X 射线晶体学的结构数据相结合，以获得系统激子性质的间接表示。在这里，提出了一种替代策略，它超越了这种经验方法，并引入了结构和电子特性及其对温度依赖性的从头算计算描述。该策略适用于紫色细菌中存在的外围光捕获天线复合体（LH2）。通过将该模型与基于晶体结构的模型进行比较，可以对吸收和圆二色性 (CD) 光谱及其温度依赖性进行详细的分子水平解释。在低温和室温下的实验获得的一致性为从原子角度理解 LH2 系统的激发动力学奠定了基础。
The spectroscopic properties of light-harvesting (LH) antennae in photosyntehtic organisms represent a fingerprint that is unique for each specific pigment protein complex. Because of that, spectroscopic observations are generally combined with structural data from X-ray crystallography to obtain an indirect representation of the excitonic properties of the system. Here, an alternative strategy is presented which goes beyond this empirical approach and introduces an ab initio computational description of both structural and electronic properties and their dependence on the temperature. The strategy is applied to the peripheral light-harvesting antenna complex (LH2) present in purple bacteria. By comparing this model with the one based on the crystal structure, a detailed, molecular level explanation of the absorption and circular dichroism (CD) spectra and their temperature dependence is achieved. The agreement obtained with the experiments at both low and room temperature lays the groundwork for an atomistic understanding of the excitation dynamics in the LH2 system.