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arXiv 1704.08076cond-mat.str-el
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基于单电子自相互作用误差的第一性原理Hubbard U参数的自洽基态公式

A self-consistent ground-state formulation of the first-principles Hubbard U parameter validated on one-electron self-interaction error

Glenn Moynihan, Gilberto Teobaldi, David D. O'Regan

摘要:

在基于近似密度泛函理论(DFT)校正系统误差的电子结构方法中,Hubbard $U$参数可用于量化和修正归因于所选子空间的自相互作用误差。在这里,为了使准确的,计算方便的计算$U$通过DFT算法,通过直接总能量最小化定位的基态,我们介绍了一个成功的线性响应方法$U$在完全放松的约束基态密度方面的重新制定。将$U$定义为基态密度的隐式泛函意味着DFT + Hubbard $U$(DFT+ $U$)总能量和相关性质的可比性,因为外部参数(如离子位置)随其相应的第一原理$U$值一起变化。我们的方法提供了一个框架,以解决部分未解决的问题,自一致性超过$U$,其中合理的计划已经提出,并精确地定义与子空间多体自相互作用错误的能量。我们表明,DFT+ $U$精确地纠正自相互作用误差在理想条件下的总能量,但只有当一个简单的自洽条件。这些参数也促进了最近提出的DFT+ $U$为基础的方法,执行Koopmans定理的第一原理。

英文摘要:

In electronic structure methods based on the correction of approximate density-functional theory (DFT) for systematic inaccuracies, Hubbard $U$ parameters may be used to quantify and amend the self-interaction errors ascribed to selected subspaces. Here, in order to enable the accurate, computationally convenient calculation of $U$ by means of DFT algorithms that locate the ground-state by direct total-energy minimization, we introduce a reformulation of the successful linear-response method for $U$ in terms of the fully-relaxed constrained ground-state density. Defining $U$ as an implicit functional of the ground-state density implies the comparability of DFT + Hubbard $U$ (DFT+$U$) total-energies, and related properties, as external parameters such as ionic positions are varied together with their corresponding first-principles $U$ values. Our approach provides a framework in which to address the partially unresolved question of self-consistency over $U$, for which plausible schemes have been proposed, and to precisely define the energy associated with subspace many-body self-interaction error. We demonstrate that DFT+$U$ precisely corrects the total energy for self-interaction error under ideal conditions, but only if a simple self-consistency condition is applied. Such parameters also promote to first-principles a recently proposed DFT+$U$ based method for enforcing Koopmans' theorem.

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