论文标题
通过复杂的系统浴耦合计算吸收型线性光谱的近似方法的准确性
Accuracy of approximate methods for the calculation of absorption-type linear spectra with a complex system-bath coupling
论文作者
论文摘要
计算线性光谱的近似方法的准确性取决于许多变量。在这项研究中，我们将大多数参数固定在植物的光合轻度收获复合物中发现的典型值，并确定近似光谱相对于精确计算的准确性，这是色素二聚体中能隙和配合偶联的函数的函数。我们使用光谱密度与前八个分子内模式的叶绿素A A，并包括不均匀疾病来计算光谱。我们比较了使用完整的累积膨胀（FCE），相干时间依赖性的Redfield（CTR）以及时间独立的Redfield和Redified Redfield方法计算的吸收，线性二色性和圆形二色性光谱的准确性。作为参考，我们使用使用精确的随机路径积分评估方法计算的光谱。我们发现FCE方法是所有光谱的计算最准确的。当颜料适度耦合时，CTR方法对于吸收和线性二分法光谱的定性计算（$ \ sim 15 \ text {cm}^{ - 1} $）的性能很好，但是当ctr spectra可能与精确的光谱差异很大时，当强烈的光谱与强烈的插入式插入插入时（$ \ sim sim sim is pext is Text $} $ sext $} $ {红场和改性红场光谱对分子参数的质量的依赖性相似，这些方法几乎总是比CTR差，尤其是当插图耦合较强或激素能量隙很小时（对于给定的耦合）。当包括现实的不均匀疾病时，近似光谱的准确性不受激子能量隙和分子内模式之间的共振的影响。
The accuracy of approximate methods for calculating linear optical spectra depends on many variables. In this study, we fix most of these parameters to typical values found in photosynthetic light-harvesting complexes of plants and determine the accuracy of approximate spectra with respect to exact calculation as a function of the energy gap and interpigment coupling in a pigment dimer. We use a spectral density with the first eight intramolecular modes of chlorophyll a and include inhomogeneous disorder for the calculation of spectra. We compare the accuracy of absorption, linear dichroism, and circular dichroism spectra calculated using the Full Cumulant Expansion (FCE), coherent time-dependent Redfield (ctR), and time-independent Redfield and modified Redfield methods. As a reference we use spectra calculated with the Exact Stochastic Path Integral Evaluation method. We find the FCE method to be the most accurate for the calculation of all spectra. The ctR method performs well for the qualitative calculation of absorption and linear dichroism spectra when pigments are moderately coupled ($\sim 15\text{ cm}^{-1}$), but ctR spectra may differ significantly from exact spectra when strong interpigment coupling ($\sim 100\text{ cm}^{-1}$) is present. The dependence of the quality of Redfield and modified Redfield spectra on molecular parameters is similar, and these methods almost always perform worse than ctR, especially when the interpigment coupling is strong or the excitonic energy gap is small (for a given coupling). The accuracy of approximate spectra is not affected by resonance between the excitonic energy gap and intramolecular modes when realistic inhomogeneous disorder is included.
