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arXiv 2008.02417cond-mat.mtrl-sci
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二维铁电体自洽Hubbard参数的第一性原理研究

First-Principles Study of Two-Dimensional Ferroelectrics Using Self-Consistent Hubbard Parameters

Jiawei Huang, Sang-Hoon Lee, Andrew Supka, Young-Woo Son, Shi Liu

发表信息：
Phys. Rev. B 102, 165157 (2020)
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摘要：

具有原子厚度的可切换自发极化的二维（2D）材料的发现为实现具有潜在应用范围从存储器和传感器到MEMS和太阳能电池的高密度电子器件开辟了令人兴奋的机会。基于密度泛函理论（DFT）的第一性原理方法促进了二维铁电体的发现和设计。然而，采用局部和半局部交换相关泛函的DFT计算未能准确地预测该低维材料家族的带隙。在这里，我们提出了一个DFT+ $U$ + $V$的二维FEs表示的单层$α$ -In $_2$ Se $_3$和它的同源III $_2$ -VI $_3$化合物的平面外和平面内的偏振，使用Hubbard参数计算的第一性原理。我们发现，ACBN 0，一个伪混合密度泛函，允许自洽确定的$U$参数，提高了所有调查的二维有限元带隙的预测与计算成本远低于混合密度泛函。位间库仑相互作用$V$对于精确描述双层In $_2$ Se $_3$和In $_2$ Se $_3$ /InTe等范德华异质结构的电子结构至关重要。对于铁基催化的研究，我们发现自洽$U$修正的应用可以强烈地影响开壳层分子在二维铁电极性表面上的吸附能。

英文摘要：

The discovery of two-dimensional (2D) materials possessing switchable spontaneous polarization with atomic thickness opens up exciting opportunities to realize ultrathin, high-density electronic devices with potential applications ranging from memories and sensors to photocatalysis and solar cells. First-principles methods based on density functional theory (DFT) have facilitated the discovery and design of 2D ferroelectrics (FEs). However, DFT calculations employing local and semilocal exchange-correlation functionals failed to predict accurately the band gaps for this family of low-dimensional materials. Here, we present a DFT+$U$+$V$ study on 2D FEs represented by single-layer $α$-In$_2$Se$_3$ and its homologous III$_2$-VI$_3$ compounds with both out-of-plane and in-plane polarization, using Hubbard parameters computed from first-principles. We find that ACBN0, a pseudo-hybrid density functional that allows self-consistent determination of $U$ parameters, improves the prediction of band gaps for all investigated 2D FEs with a computational cost much lower than the hybrid density functional. The inter-site Coulomb interaction $V$ becomes critical for accurate descriptions of the electronic structures of van der Waals heterostructures such as bilayer In$_2$Se$_3$ and In$_2$Se$_3$/InTe. Pertinent to the study of FE-based catalysis, we find that the application of self-consistent $U$ corrections can strongly affect the adsorption energies of open-shell molecules on the polar surfaces of 2D FEs.

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