Consistent LDA’ + DMFT—an unambiguous way to avoid double counting problem: NiO test
Consistent LDA’ + DMFT—an unambiguous way to avoid double counting problem: NiO test
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一致的 LDA’ + DMFT——避免重复计算问题的明确方法：NIO 测试
DOI：
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发表时间：
2012
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通讯作者：
M. V. Sadovskii
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作者：
I. Nekrasov;V. Pavlov;M. V. Sadovskii
我们提出了一种一致的方法来处理在LDA+DMFT组合方法中不可避免地出现的重复计数问题，以实际计算强关联体系的电子结构。这里的主要障碍是缺乏系统的(例如图解)方法来表达密度泛函理论中出现的局域密度近似对交换关联能的贡献。目前还不清楚，通过LDA计算，进入DMFT(动力学平均场理论)的相互作用的哪一部分已经被考虑在内。正因为如此，到目前为止，LDA+DMFT中的重复计数校正还没有一个公认的唯一表达式。为了避免这个问题，我们提出了一致的LDA‘+DMFT方法，在自洽能带结构计算过程中，对于相关的态(带)，LDA交换关联贡献被显式排除。对于那些强关联的态(带)，库仑相互作用被忽略的是它的非局域部分，它没有包括在DMFT中，以及局域的哈特里贡献。然后，重复计数校正被唯一地简化为局部哈特里贡献。然后，通过标准的DMFT直接解释强关联状态的关联。我们进一步测试了一致的LDA‘+DMFT方法，并与传统的LDA+DMFT方法进行了比较，计算了NiO的电子结构。与传统的LDA+DMFT方法相反，我们一致的LDA‘+DMFT方法毫不含糊地产生了与实验一致的绝缘带结构。
We present a consistent way of treating a double counting problem unavoidably arising within the LDA + DMFT combined approach to realistic calculations of electronic structure of strongly correlated systems. The main obstacle here is the absence of systematic (e.g., diagrammatic) way to express LDA (local density approximation) contribution to exchange correlation energy appearing in the density functional theory. It is not clear then, which part of interaction entering DMFT (dynamical mean-field theory) is already taken into account through LDA calculations. Because of that, up to now there is no accepted unique expression for the double counting correction in LDA + DMFT. To avoid this problem we propose here the consistent LDA’ + DMFT approach, where LDA exchange correlation contribution is explicitly excluded for correlated states (bands) during self-consistent band structure calculations. What is left out of Coulomb interaction for those strongly correlated states (bands) is its non-local part, which is not included in DMFT, and the local Hartreelike contribution. Then the double counting correction is uniquely reduced to the local Hartree contribution. Correlations for strongly correlated states are then directly accounted for via the standard DMFT. We further test the consistent LDA’ + DMFT scheme and compare it with conventional LDA + DMFT calculating the electronic structure of NiO. Opposite to the conventional LDA + DMFT our consistent LDA’ + DMFT approach unambiguously produces the insulating band structure in agreement with experiments.