论文标题
核心孔光发射累积扩展中的非线性响应
Non-linear response in the cumulant expansion for core hole photoemission
论文作者
论文摘要
在多体扰动理论的框架中，当前使用的大多数用于单粒子绿色的功能g，例如Hedin的GW近似值或累积的GW+C方法，基于筛选相互作用的线性响应近似。在这里，我们展示了如何从绿色函数的运动方程式中在功能衍生式公式中的运动方程式获得累积绿色的函数。结果可以以紧凑的形式编写，这打开了使用时间依赖性密度功能理论在第一原理框架中计算校正的可能性。为了说明校正的潜在重要性，为具有核心水平和两个价轨道的模型系统提供了数值结果。
Most currently used approximations for the one-particle Green's function G in the framework of many-body perturbation theory, such as Hedin's GW approximation or the cumulant GW+C approach, are based on a linear response approximation for the screened interaction W. The extent to which such a hypothesis is valid and ways to go beyond have been explored only very little. Here we show how to derive a cumulant Green's function beyond linear-response from the equation of motion of the Green's function in a functional derivative formulation. The results can be written in a compact form, which opens the possibility to calculate the corrections in a first principles framework using time-dependent density functional theory. In order to illustrate the potential importance of the corrections, numerical results are presented for a model system with a core level and two valence orbitals.
