[Wannier] Discrepancy between Wannier90 and DFT band structures

[Azin Kazemi Moridani]

Dear All, I am trying to generate a Wannier90 tight-binding model for Sr2FeO4 using Wannier90 interfaced with ABINIT. The overall behavior of the bands produced by Wannier90 and ABINIT agree with one another, but there are some discrepancies almost everywhere, especially around the Fermi energy. I have tried to investigate the effect of varying different parameters, such as : size of the KPOINT mesh, number of iterations, energy window (with and without a frozen window, excluding bands,..), and the set of projections (either only on Iron d-orbitals, or on Iron d-orbitals plus Oxygen p-orbitals). In the disentangled case of Iron d-orbitals plus Oxygen p-orbitals, the mapping is expected to be exactly on top of the DFT band structure. I performed the calculations with two pseudopotentials, Norm-Conserving (NC) and Projector-Augmented Wave (PAW). In all the cases, convergence is achieved but the disagreement persists.
I would appreciate it a lot if anyone could help me improve my results. The “wannier90.win<http://wannier90.win>" and "wannier90.wout” files alongside the band structures in the case of five Iron d-orbitals (NC5.PNG) and five Iron d-orbitals plus twelve (4 * 3) Oxygen p-orbitals (NC17.PNG) can be found here:
https://drive.google.com/drive/folders/1WDjjKl22XXsIW7sdPIbWEsz29ZnkMTGO?usp=sharing

Thank you so much in advance.

Best Regards,
Mohaddeseh Kazemi-Moridani
Department of Physics
Université de Montréal

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