钙钛矿材料能带穿越费米能级的问题

wmy

最近算sn基钙钛矿材料的能带时，发现在费米面有能带，并且相应的带隙算为负值。但是光学带隙为3点几，而且钙钛矿应该是半导体啊。这是因为没有考虑磁性的原因吗，还是因为没有考虑加u呢。

sobereva

如果之前用的纯泛函，+U或者杂化泛函再试

njust-lbc

您好，请问您这个问题后来解决了吗，我最近用CP2K中HLE17计算MOF带隙时也出现了类似的情况。

Ylucky

你好，您的这个问题解决了吗，我目前计算也出现了这个问题

wmy

Ylucky 发表于 2024-7-5 11:30
你好，您的这个问题解决了吗，我目前计算也出现了这个问题

+U

wmy

在一篇文献中看到了这个解释：
1. 计算下紫外光谱，看和实验拟合得到的差别。如果差别不大，可以用以下解释。https://www.nature.com/articles/s41467-023-41560-8#citeas
For a deeper understanding of the electronic structure, the density of electronic states (DOS) is
calculated by DFT. However, the calculated electronic band gap is very narrow (0.11 eV) and
contrary to the result acquired from the Tauc plot (Supplementary Fig. 25a). This inconsistency
might result from a forbidden transition of photons and could be understood through the optical
absorption coefficient. The calculated optical absorption band gap (1.67 eV) is consistent with the
experimental value and no near-infrared absorption is observed, which indicates that the calculated
electronic band gap of 0.11 eV is forbidden. According to the charge density plots, the electrons
excited by optical absorption are transferred from O and N ions to neighboring C ions.