Multiple impurities and combined local density approximations in site-occupation embedding theory
Multiple impurities and combined local density approximations in site-occupation embedding theory
复制标题
DOI：
10.1007/s00214-018-2368-z
复制
发表时间：
2018-06
影响因子：
1.7
通讯作者：
Bruno Senjean;N. Nakatani;M. Tsuchiizu;Emmanuel Fromager
中科院分区：
文献类型：
--
作者：
Bruno Senjean;N. Nakatani;M. Tsuchiizu;Emmanuel Fromager
位点嵌入理论 (SOET) 是模型哈密顿量密度泛函理论的原则上精确的多行列式扩展。这项工作探讨了 SOET 最新发展的各种扩展（Senjean 等人，在 Phys Rev B 97:235105, 2018）。向前迈出的重要一步是将理论推广到多种杂质位点。我们还提出了一种新的单杂质密度泛函近似（DFA），其中两能级（2L）哈伯德系统的密度泛函杂质相关能与 Bethe ansatz 局部密度近似（BALDA）相结合，得到（无限）哈伯德模型的完全相关能。为了测试新的 DFA，我们使用密度矩阵重整化群方法 (DMRG) 自洽地计算了杂质相互作用波函数。在一维情况下导出并实现了双重占据和每位点能量表达式。对结果进行了详细分析，特别关注单独由能量泛函或自洽收敛密度引起的误差。在所有 DFA（包括之前提出的 DFA）中，组合的 2L-BALDA 是在所有相关性和密度范围内表现最好的一种。最后，作为一个视角，简要讨论了新方向的扩展，例如 SOET 的分区 DFT 型重新表述、基于投影的 SOET 方法或 SOET 与格林函数的组合。
Site-occupation embedding theory (SOET) is an in-principle-exact multi-determinantal extension of density-functional theory for model Hamiltonians. Various extensions of recent developments in SOET (Senjean et al. in Phys Rev B 97:235105, 2018) are explored in this work. An important step forward is the generalization of the theory to multiple-impurity sites. We also propose a new single-impurity density-functional approximation (DFA) where the density-functional impurity correlation energy of the two-level (2L) Hubbard system is combined with the Bethe ansatz local density approximation (BALDA) to the full correlation energy of the (infinite) Hubbard model. In order to test the new DFAs, the impurity-interacting wavefunction has been computed self-consistently with the density-matrix renormalization group method (DMRG). Double occupation and per-site energy expressions have been derived and implemented in the one-dimensional case. A detailed analysis of the results is presented, with a particular focus on the errors induced either by the energy functionals solely or by the self-consistently converged densities. Among all the DFAs (including those previously proposed), the combined 2L-BALDA is the one that performs the best in all correlation and density regimes. Finally, extensions in new directions, like a partition-DFT-type reformulation of SOET, a projection-based SOET approach, or the combination of SOET with Green functions, are briefly discussed as a perspective.