用守恒Bethe-Salpeter方程方法研究有限系统的光吸收谱
Optical absorption spectra of finite systems from a conserving Bethe-Salpeter equation approach
摘要：
我们提出了一种计算光学吸收谱的方法，通过Bethe-Salpeter方程的方法，这是基于一个保守的线性响应计算的电子空穴相干在外部电磁场的存在下。这个过程允许，在原则上，为确定的电子-空穴关联函数自洽与相应的单粒子格林函数。我们分析了一般的方法为“一次性”计算的光吸收截面的有限系统，并讨论了在这种方法中的散射和退相贡献的重要性。我们将此方法应用于闭壳层团簇Na_4、Na^+_9和Na^+_（21），每个Na原子处理一个活性电子。
英文摘要：
We present a method for computing optical absorption spectra by means of a Bethe-Salpeter equation approach, which is based on a conserving linear response calculation for electron-hole coherences in the presence of an external electromagnetic field. This procedure allows, in principle, for the determination of the electron-hole correlation function self-consistently with the corresponding single-particle Green function. We analyze the general approach for a "one-shot" calculation of the photoabsorption cross section of finite systems, and discuss the importance of scattering and dephasing contributions in this approach. We apply the method to the closed-shell clusters Na_4, Na^+_9 and Na^+_(21), treating one active electron per Na atom.
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