发表机构
Université de Toulouse, CNRS; University of Hamburg; The Hamburg Centre for Ultrafast Imaging (CUI)（图卢兹大学，法国国家科学研究中心; 汉堡大学; 汉堡超快成像中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文对比Bogoliubov自洽GW与二阶格林函数方法，发现后者在吸引性Hubbard模型中更准确，GW高估关联能，凸显交换贡献的重要性。
AI 中文摘要
描述具有吸引相互作用的费米子系统（如超导体和原子核）超越平均场水平仍然是一个核心挑战。在本工作中，我们研究了Bogoliubov完全自洽$GW$（Bog. scGW）和二阶格林函数（Bog. scGF2）方法的性能，这些方法在统一的虚时和虚频框架内实现。以吸引性Hubbard模型为基准，与完全组态相互作用（FCI）对比，我们发现Bog. scGF2比Bog. scGW提供了更准确的描述。特别是，Bog. scGW系统地高估了关联能，且误差随着吸引相互作用强度的增加而迅速增大。这些结果强调了交换贡献在强关联费米子系统中的重要性，即使交换效应仅以低阶微扰论包含在内。
英文摘要
Describing fermionic systems with attractive interactions, such as superconductors and atomic nuclei, beyond the mean-field level remains a central challenge. In this work, we investigate the performance of Bogoliubov fully self-consistent $GW$ (Bog.~sc$GW$) and second-order Green's function (Bog.~scGF2) methods, implemented within a unified imaginary-time and imaginary-frequency framework. Using the attractive Hubbard model as a benchmark against full configuration interaction (FCI), we find that Bog. scGF2 provides a more accurate description than Bog.~sc$GW$. In particular, Bog.~sc$GW$ systematically overestimates the correlation energy, with errors increasing rapidly as the attractive interaction strength grows. These results highlight the importance of exchange contributions in strongly correlated fermionic systems, even when exchange effects are included only at low order in perturbation theory.
Comments16 pages, 2 figures (Supporting Information available)
