Zhang Min-Ye, Jiang Hong
Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing, China.
Front Chem. 2021 Sep 28;9:747972. doi: 10.3389/fchem.2021.747972. eCollection 2021.
The pyrite and marcasite polymorphs of FeS have attracted considerable interests for their potential applications in optoelectronic devices because of their appropriate electronic and optical properties. Controversies regarding their fundamental band gaps remain in both experimental and theoretical materials research of FeS. In this work, we present a systematic theoretical investigation into the electronic band structures of the two polymorphs by using many-body perturbation theory with the approximation implemented in the full-potential linearized augmented plane waves (FP-LAPW) framework. By comparing the quasi-particle (QP) band structures computed with the conventional LAPW basis and the one extended by high-energy local orbitals (HLOs), denoted as LAPW + HLOs, we find that one-shot or partially self-consistent ( and , respectively) on top of the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation with a converged LAPW + HLOs basis is able to remedy the artifact reported in the previous calculations, and leads to overall good agreement with experiment for the fundamental band gaps of the two polymorphs. Density of states calculated from @PBE with the converged LAPW + HLOs basis agrees well with the energy distribution curves from photo-electron spectroscopy for pyrite. We have also investigated the performances of several hybrid functionals, which were previously shown to be able to predict band gaps of many insulating systems with accuracy close or comparable to . It is shown that the hybrid functionals considered in general fail badly to describe the band structures of FeS polymorphs. This work indicates that accurate prediction of electronic band structure of FeS poses a stringent test on state-of-the-art first-principles approaches, and the method based on semi-local approximation performs well for this difficult system if it is practiced with well-converged numerical accuracy.
FeS的黄铁矿和白铁矿多晶型物因其合适的电子和光学性质，在光电器件中的潜在应用引起了相当大的兴趣。在FeS的实验和理论材料研究中，关于其基本带隙仍存在争议。在这项工作中，我们使用全势线性缀加平面波（FP-LAPW）框架中实现的近似的多体微扰理论，对这两种多晶型物的电子能带结构进行了系统的理论研究。通过比较用传统LAPW基组计算的准粒子（QP）能带结构和由高能局域轨道（HLOs）扩展的能带结构（表示为LAPW + HLOs），我们发现，在具有收敛的LAPW + HLOs基组的Perdew-Burke-Ernzerhof（PBE）广义梯度近似之上进行一次性或部分自洽（分别为 和 ），能够纠正先前计算中报告的伪像，并导致与两种多晶型物的基本带隙的实验结果总体上良好吻合。用收敛的LAPW + HLOs基组从@PBE计算的态密度与黄铁矿的光电子能谱的能量分布曲线吻合良好。我们还研究了几种杂化泛函的性能，这些杂化泛函先前已被证明能够以接近或可比的精度预测许多绝缘系统的带隙。结果表明，所考虑的杂化泛函通常无法很好地描述FeS多晶型物的能带结构。这项工作表明，准确预测FeS的电子能带结构对当前的第一性原理方法提出了严峻考验，并且基于半局域近似的 方法如果以良好收敛的数值精度实施，对于这个困难的系统表现良好。
