Fritzsche Stephan, Surzhykov Andrey
Helmholtz-Institut Jena, Fröbelstieg 3, D-07743 Jena, Germany.
GSI Helmholtzzentrum für Schwerionenforschung, D-64291 Darmstadt, Germany.
Molecules. 2021 May 1;26(9):2660. doi: 10.3390/molecules26092660.
In atomic and many-particle physics, Green functions often occur as to formally represent the (integration over the) complete spectrum of the underlying Hamiltonian. However, while these functions are very crucial to describing many second- and higher-order perturbation processes, they have hardly been considered and classified for complex atoms. Here, we show how relativistic (many-electron) Green functions can be approximated and systematically improved for few- and many-electron atoms and ions. The representation of these functions is based on of virtual excitations, or so-called , with regard to given bound-state reference configurations, and by applying a multi-configuration Dirac-Hartree-Fock expansion of all atomic states involved. A first implementation of these approximate Green functions has been realized in the framework of Jac, the Jena Atomic Calculator, and will facilitate the study of various multi-photon and/or multiple electron (emission) processes.
在原子物理和多粒子物理中，格林函数经常出现，以便形式上表示基础哈密顿量的完整谱（对其进行积分）。然而，尽管这些函数对于描述许多二阶及更高阶微扰过程非常关键，但对于复杂原子，它们几乎未被考虑和分类。在这里，我们展示了相对论性（多电子）格林函数如何针对少电子和多电子原子及离子进行近似并系统地改进。这些函数的表示基于相对于给定束缚态参考构型的虚拟激发，即所谓的，以及通过对所有涉及的原子态应用多组态狄拉克 - 哈特里 - 福克展开。这些近似格林函数的首次实现是在雅可比（耶拿原子计算器）的框架内完成的，这将有助于研究各种多光子和/或多电子（发射）过程。
