Electronic structure of chromium trihalides beyond density functional theory
Abstract
We explore the electronic band structure of freestanding monolayers of chromium trihalides Cr X3 , 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 (QS G W ̂) 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 Γ point. By analyzing the dynamic and momentum-dependent self-energy, we show that QS G W ̂ 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 QS G W ̂ 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.
- Publication:
-
Physical Review B
- Pub Date:
- October 2021
- DOI:
- 10.1103/PhysRevB.104.155109
- arXiv:
- arXiv:2106.06564
- Bibcode:
- 2021PhRvB.104o5109A
- Keywords:
-
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- Phys. Rev. B 104, 155109 (2021)