Electronic structure of chromium trihalides beyond density functional theory
Electronic structure of chromium trihalides beyond density functional theory
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DOI：
10.1103/physrevb.104.155109
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发表时间：
2021-10-05
影响因子：
3.7
通讯作者：
Katsnelson, Mikhail, I
中科院分区：
文献类型：
--
作者：
Acharya, Swagata;Pashov, Dimitar;Katsnelson, Mikhail, I
我们探讨了三卤化铬CrX 3，X = Cl，Br，I的独立单分子膜的电子能带结构，在一个先进的从头计算理论方法的基础上使用绿色的功能泛函。通过求解粒子-空穴阶梯Bethe-Salpeter方程，将局域密度近似与准粒子自洽GW（QSGW）近似及其在帽上的自洽扩展（QSG（W）over cap）进行了比较.我们表明，在所有水平的理论，价带一致地改变形状的顺序Cl -> Br -> I，和价带的最大值从M点转移到伽马点。通过分析动力学和动量相关的自能，我们表明，QSG（W）的上限增加了本地化的系统相比，QSGW，从而导致一个更窄的带和减少量的卤素的价带流形。进一步的分析表明，随着Cr d和Xp之间的杂化作用在Cl -> Br -> I ->方向上增强，X = Cl的相关性最强，而X = I的相关性最小（最像带）。对于CrBr 3和CrI 3，我们观察到QSGW和QSG（W）在帽状价带结构上的显著差异，而它们的本征函数非常相似。我们发现，弱扰动，如适度的应变，弱的变化的d-p杂化，并添加小U，可以翻转这两种解决方案之间的价带结构在这些材料。
We explore the electronic band structure of freestanding monolayers of chromium trihalides CrX3, X = Cl, Br, I, within an advanced ab initio theoretical approach based on the use of Green's function functionals. We compare the local density approximation with the quasiparticle self-consistent GW (QSGW) approximation and its self-consistent extension (QSG (W) over cap) by solving the particle-hole ladder Bethe-Salpeter equations to improve the effective interaction W. We show that, at all levels of theory, the valence band consistently changes shape in the sequence Cl -> Br -> I, and the valence band maximum shifts from the M point to the Gamma point. By analyzing the dynamic and momentum-dependent self-energy, we show that QSG (W) over cap adds to the localization of the systems in comparison with QSGW, thereby leading to a narrower band and reduced amount of halogens in the valence band manifold. Further analysis shows that X = Cl is most strongly correlated, and X = I is least correlated (most bandlike) as the hybridization between Cr d and X p enhances in the direction Cl -> Br -> I -> For CrBr3 and CrI3, we observe remarkable differences between the QSGW and QSG (W) over cap valence band structures, while their eigenfunctions are very similar. We show that weak perturbations, like moderate strain, weak changes to the d-p hybridization, and adding small U, can flip the valence band structures between these two solutions in these materials.