[QE-users] [ DFT+U ] DOS for closed-shell systems

[Lucas Francisco Rodriguez Almeida]

Dear users of QE,

I was running some tests with LiCoO2 within the DFT+U(+V) framework. I decided to compare the DOS obtained by such results and also with the results form materials project (mp-22526). See attached figure.

[https://res.public.onecdn.static.microsoft/assets/mail/file-icon/png/photo_16x16.png]DOS_DFT_MP_UV.png<https://politoit-my.sharepoint.com/:i:/g/personal/lucas_rodriguez_polito_it/EXbhSFxTZgxAk9NHsARA0fIBIpkkw4Wl4OWcb8tJlNNUdw>

I expected overestimated U values coming from LR using the hp.x code (U Co-3d ~ 7.7 eV), so that the band gap coming from my results are somewhat high (yellow and red lines in the Fig.).

What was interesting to me that the results from materials project (which employ DFT+U(+J), with U_eff values coming from LR – see Moore, G. C. et al. Phys. Rev. Mat. 2024) seem to give accurate band gaps (experiments give ~2-2.7 eV). Additionally, it seems that the Co-3d orbitals are closer to the Ef, which gives a more reasonable picture of the electronic structure.

How can this be explained considering we are employing the same method? Is it just the inclusion of J values together with the reduction in the U values (considering VASP uses other projectors, PPs...)?

My initial doubt was coming from the fact that I was unsure how to treat closed-shell systems within the DFT+U framework, before seeing the results in materials project I was planning to test out the U_eff values that I can get from ACBN0, but it is not straightforward...

Any insights/comments would be appreciated
Best,


Lucas F. Rodriguez
PhD student @ University of Bologna
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