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arXiv 1605.08643cond-mat.mtrl-scicond-mat.str-el
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多体微扰理论对无规相近似的屏蔽交换修正

Screened exchange corrections to the random phase approximation from many-body perturbation theory

Felix Hummel, Andreas Grüneis, Georg Kresse, Paul Ziesche

摘要:

无规相位近似(RPA)系统地高估了相关能的大小,通常低估了内聚能。这部分源于完全缺乏交换条件,否则将取消违反泡利不相容原理(EPV)的贡献。未抵消的EPV贡献也表现为接近电子-电子聚结的自旋平行电子的非物理负对密度的形式。我们遵循多体微扰理论的考虑,提出了一个交换校正,纠正了最大的EPV贡献集,同时具有尽可能低的计算复杂度。所提出的方法交换RPA图中相邻的粒子/空穴对,大大提高了自旋平行电子的对密度接近聚结的均匀电子气(UEG)。相关能的准确性与二阶屏蔽交换(SOSEX)校正的其他变体相当,尽管它对于自旋极化的UEG稍微更准确。其计算复杂度分别为轨道空间或实空间中的$\mathcal O(N^5)$或$\mathcal O(N^4)$。它的内存需求为$\mathcal O(N^2)$。

英文摘要:

The random phase approximation (RPA) systematically overestimates the magnitude of the correlation energy and generally underestimates cohesive energies. This originates in part from the complete lack of exchange terms, which would otherwise cancel Pauli exclusion principle violating (EPV) contributions. The uncanceled EPV contributions also manifest themselves in form of an unphysical negative pair density of spin-parallel electrons close to electron-electron coalescence. We follow considerations of many-body perturbation theory to propose an exchange correction that corrects the largest set of EPV contributions while having the lowest possible computational complexity. The proposed method exchanges adjacent particle/hole pairs in the RPA diagrams, considerably improving the pair density of spin-parallel electrons close to coalescence in the uniform electron gas (UEG). The accuracy of the correlation energy is comparable to other variants of Second Order Screened Exchange (SOSEX) corrections although it is slightly more accurate for the spin-polarized UEG. Its computational complexity scales as $\mathcal O(N^5)$ or $\mathcal O(N^4)$ in orbital space or real space, respectively. Its memory requirement scales as $\mathcal O(N^2)$.

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