论文标题
部分可观测时空混沌系统的无模型预测
Nonlocal corrections to dynamical mean-field theory from the two-particle self-consistent method
论文作者
论文摘要
对于Hubbard模型，仍在开发用于短距离观测值和长波长集体模式的理论方法。在这里，我们基于一种将动态平均场理论（DMFT）与两粒子自洽理论（TPSC）结合在一起的方法。这提供了一种在DMFT中包括非本地相关性的方法，同时也改善了TPSC。这些基准是为二维方格晶格哈伯德模型发布的图形量子蒙特卡洛结果，并具有最近的邻居跳跃。该方法（TPSC+DMFT）与弱与中间相互作用有关，满足当地的Pauli原理，并允许我们计算满足Mermin-Wagner定理的自旋敏感性。 DMFT双重占用率通过局部旋转和充电总和来确定旋转和电荷顶点。通过用局部DMFT自我能源代替其本地部分，TPSC的自能量也可以改善。通过这种方法，我们发现自旋和电荷波动以及自我能源的改进。我们还发现，为TPSC开发的精度检查是该模型与基准偏差的良好预测指标。 TPSC+DMFT可用于量子蒙特卡洛无法访问的方案。另外，此方法为TPSC的多波段概括铺平了道路，该方法可用于包括DMFT在内的高级电子结构代码。
Theoretical methods that are accurate for both short-distance observables and long-wavelength collective modes are still being developed for the Hubbard model. Here, we benchmark an approach that combines dynamical mean-field theory (DMFT) observables with the two-particle self-consistent theory (TPSC). This offers a way to include non-local correlations in DMFT while also improving TPSC. The benchmarks are published diagrammatic quantum Monte Carlo results for the two-dimensional square lattice Hubbard model with nearest-neighbor hopping. This method (TPSC+DMFT) is relevant for weak to intermediate interaction, satisfies the local Pauli principle and allows us to compute a spin susceptibility that satisfies the Mermin-Wagner theorem. The DMFT double occupancy determines the spin and charge vertices through local spin and charge sum rules. The TPSC self-energy is also improved by replacing its local part with the local DMFT self-energy. With this method, we find improvements for both spin and charge fluctuations and for the self-energy. We also find that the accuracy check developed for TPSC is a good predictor of deviations from benchmarks for this model. TPSC+DMFT can be used in regimes where quantum Monte Carlo is inaccessible. In addition, this method paves the way to multi-band generalizations of TPSC that could be used in advanced electronic structure codes that include DMFT.
