Förster Arno, Bruneval Fabien
Theoretical Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands.
Université Paris-Saclay, CEA, Service de recherche en Corrosion et Comportement des Matériaux, SRMP, 91191 Gif-sur-Yvette, France.
J Phys Chem Lett. 2024 Dec 26;15(51):12526-12534. doi: 10.1021/acs.jpclett.4c03126. Epub 2024 Dec 13.
Hedin's approximation to the electronic self-energy has been impressively successful in calculating quasiparticle energies, such as ionization potentials, electron affinities, or electronic band structures. The success of this fairly simple approximation has been ascribed to the cancellation of the so-called vertex corrections that go beyond the approximation. This claim is mostly based on past calculations using vertex corrections within the crude local-density approximation. Here, we explore a wide variety of nonlocal vertex corrections in the polarizability and the self-energy, using first-order approximations or infinite summations to all orders. In particular, we use vertices based on statically screened interactions like in the Bethe-Salpeter equation. We demonstrate on realistic molecular systems that the two vertices in Hedin's equation essentially compensate. We further show that consistency between the two vertices is crucial for obtaining realistic electronic properties. We finally consider increasingly large clusters and extrapolate that our conclusions about the compensation of the two vertices would hold for extended systems.
赫丁对电子自能的近似在计算准粒子能量方面取得了令人瞩目的成功，例如电离势、电子亲和能或电子能带结构。这种相当简单的近似方法的成功归因于超越该近似的所谓顶点修正的抵消。这一说法主要基于过去在粗糙的局域密度近似下使用顶点修正的计算。在这里，我们使用一阶近似或对所有阶次的无穷求和，探索极化率和自能中各种各样的非局域顶点修正。特别是，我们使用基于像在贝特 - 萨尔皮特方程中那样的静态屏蔽相互作用的顶点。我们在实际分子系统上证明，赫丁方程中的两个顶点基本上相互补偿。我们进一步表明，两个顶点之间的一致性对于获得现实的电子性质至关重要。我们最后考虑越来越大的团簇，并推断我们关于两个顶点补偿的结论对于扩展系统也成立。
