构建密度泛函或格林函数泛函的策略：我们能学到什么？
Strategies to build functionals of the density, or functionals of Green's functions: what can we learn?
摘要：
多体问题一般不能精确求解，最突出的近似之一是建立微扰展开。展开式的种类繁多，不同之处在于展开的量、展开变量、起始点以及如何求和或终止级数。虽然已经讨论了很多，也做了很多工作，但由于历史原因，特别是有限的计算或存储能力，做出了一些选择。本工作的目的是研究的理由，在不同的情况下作出不同的选择，通过比较成分的泛函的基础上\GF的一边，并在另一边的电荷密度。特别令人感兴趣的问题是如何建立一个最佳的出发点的近似非本地量，利用近或远的远见，并敢于考虑模型超越均匀的电子气。这将包括使用连接器近似。我们还将讨论为什么建立密度泛函是一个好主意。
英文摘要：
The many-body problem can in general not be solved exactly, and one of the most prominent approximations is to build perturbation expansions. A huge variety of expansions is possible, which differ by the quantity to be expanded, the expansion variable, the starting point, and ideas how to resum or terminate the series. Although much has been discussed and much has been done, some choices were made for historical reasons, in particular, limited computation or storage capacities. The present work aims at examining the justifications for different choices made in different contexts, by comparing ingredients of functionals based on \GF s on one side, and on the charge density on the other side. Of particular interest will be the question of how to build an optimal starting point for the approximation of non-local quantities, making use of near- or far-sightedness, and daring to consider models beyond the homogeneous electron gas. This will include the use of connector approximations. We will also discuss why it is a good idea to build functionals of the density.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
