Npj Comput. Mater.: 自由电子金属—原来可以这样做电子关联！
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根据电子间相互作用的强弱，材料通常可以被分为弱关联系统和强关联系统。局域密度近似下的密度泛函理论(DFT)，通过电子密度将晶体内空间中的点映射为均匀电子气问题，对弱关联材料的定性描述相当成功。然而，传统DFT是一种基态理论，对中等强度关联材料激发态特性的描述也存在困难。另一方面，在过去的几十年里，人们一直在努力开发微扰、随机或杂化泛函等方法来理解强关联和激发态特性。meta-GGAs、杂化泛函、GW近似和DFT+ 动态平均场理论(DMFT)等被统称为“beyond-DFT”的方法，且在理解固体材料方面得到广泛应用。Beyond-DFT通常应用于开壳d电子系统，可以对DFT的进行定性校正，但人们对这些方法在中等强度关联固体上的适用性知之甚少。特别是DFT + eDMFT方法，在描述局域d和f电子系统的电子结构方面广受欢迎，但其主要应用于强关联系统，对弱耦合极限方面的扩展很少讨论。类似地，meta-GGAs、杂化泛函和GW等方法也主要应用于具有强或中等相互作用的绝缘材料，但尚不清楚这些方法是否可以同样成功应用于弱关联或中等关联得金属系统中。
该文近期发表于npj Computational Materials 8：181(2022)，英文标题与摘要如下，点击左下角“阅读原文”可以自由获取论文PDF。
Electronic correlation in nearly free electron metals with beyond-DFT methods
Subhasish Mandal, Kristjan Haule, Karin M. Rabe & David Vanderbilt
For more than three decades, nearly free-electron elemental metals have been a topic of debate because the computed bandwidths are significantly wider in the local density approximation to density-functional theory (DFT) than indicated by angle-resolved photoemission (ARPES) experiments. Here, we systematically investigate this using first principles calculations for alkali and alkaline-earth metals using DFT and various beyond-DFT methods such as meta-GGA, G0W0, hybrid functionals (YS-PBE0, B3LYP), and LDA + eDMFT. We find that the static non-local exchange, as partly included in the hybrid functionals, significantly increase the bandwidths even compared to LDA, while the G0W0 bands are only slightly narrower than in LDA. The agreement with the ARPES is best when the local approximation to the self-energy is used in the LDA + eDMFT method. We infer that even moderately correlated systems with partially occupied s orbitals, which were assumed to approximate the uniform electron gas, are very well described in terms of short-range dynamical correlations that are only local to an atom.
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