[Wannier] Enquiry about the Failure in Wannierization Calculation
Kenan Song
kenan.song at kaust.edu.sa
Thu Apr 1 12:55:50 CEST 2021
Dear Stepan,
Thank you for the suggestion.
I used the same VASP code (version 5.4.4) to do the calculation for these
two calculations. The only difference is that I set NBANDS flag as 112 and
96 respectively in order to interface with WANNIER90 code but I found that
the first wannierization with num_bands=112 could be done successfully;
while the second one with num_bands=96 failed. All other parameters in the
wannierization step are the same.
In the DFT self-consistent calculation, the fermi energy level is located
at 8.51 eV and the WANNIER90 code took this value as the Fermi level in its
calculations. The minimum eigen value/band is located at -55 eV but they
are just 6 highly localised bands (straight lines) and I am interested in
bands close to Fermi energy level. This is why I choose dis_win_min as -0.5
eV.
I could use larger values (160 ~ 200) for num_bands flag but I am afraid
that the dis_win_max flag needs to be set up as an even higher value. I am
not sure whether the same error message (dis_windows: Energy window
contains fewer states than number of target WFs) would pop up.
Would you please give me some more suggestions/comments? Thank you so much
for your help.
Kind regards,
Kenan Song
Post Doctor in KAUST
On Thu, Apr 1, 2021 at 12:06 PM Stepan Tsirkin <tsirkinss at gmail.com> wrote:
> Dear Kenan,
>
> do you meant that hte first (successful) calculation was done with another
> code (not VASP) ?
>
> Different codes may produce bandstructures shifted, also depending on
> pseudopotential there might be a different number of semi-core electrons
> included. Are you sure all your bands are above the dis_win_min = -0.5
>
> If you remove dis_win_min and dis_win_max - then all bands will be
> included.
>
> However, for a good disentanglement, typically a much larger number of
> bands should be included, then the number of Wannier functions. I would
> use at least a double, i.e. num_bands~= 160-200.
>
> Regards,
>
> Stepan Tsirkin,
> University of Zurich.
> http://wannier-berri.org
> <https://urldefense.com/v3/__http://wannier-berri.org__;!!Nmw4Hv0!mcRhIZFtkkQwIAT8TyKbCdjzSk8IetfWcmjwpRZp-udWAbKcLoQ1Q9Vamt-4HoG-iizG$>
> On 01.04.21 10:49, Kenan Song wrote:
>
> Dear All,
>
> Can I ask a question?
>
> I am running the wannierization now and it could be done successfully with
> the following parameter settings in the wannier90.win file.
>
> num_wann = 80
> num_bands = 112
>
> num_iter = 50
> guiding_centres = .true.
> dis_num_iter = 1000
>
> dis_froz_min = -0.5
> dis_froz_max = 15.0
> dis_win_min = -0.5
> dis_win_max = 150.0
>
> spinors = .true.
> begin projections
> Ni : s; p; d
> N : s; p
> Mn : s; p; d
> end projections
>
> begin unit_cell_cart
> 3.8784000000 0.0000000000 0.0000000000
> 0.0000000000 3.8784000000 0.0000000000
> 0.0000000000 0.0000000000 3.8784000000
> end unit_cell_cart
>
> begin atoms_cart
> Ni 0.000000000 0.000000000 0.000000000
> N 0.500000000 0.500000000 0.500000000
> Mn 0.000000000 0.500000000 0.500000000
> Mn 0.500000000 0.000000000 0.500000000
> Mn 0.500000000 0.500000000 0.000000000
> end atoms_cart
>
> write_hr = .true.
> bands_plot = .true.
> bands_num_points = 100
> begin kpoint_path
> Gamma 0.0 0.0 0.0 X 0.0 0.5 0.0
> X 0.0 0.5 0.0 M 0.5 0.5 0.0
> M 0.5 0.5 0.0 R 0.5 0.5 0.5
> R 0.5 0.5 0.5 Gamma 0.0 0.0 0.0
> Gamma 0.0 0.0 0.0 M 0.5 0.5 0.0
> M 0.5 0.5 0.0 R 0.5 0.5 0.5
> R 0.5 0.5 0.5 X 0.0 0.5 0.0
> end kpoint_path
> bands_plot_format = gnuplot
>
> mp_grid = 21 21 21
>
> begin kpoints
> 0.000000000000 0.000000000000 0.000000000000
> 0.047619047619 0.000000000000 0.000000000000
> 0.095238095238 0.000000000000 0.000000000000
> ...
> -0.476190476190 0.476190476190 -0.476190476190
> 0.476190476190 0.476190476190 -0.476190476190
> -0.476190476190 -0.476190476190 0.476190476190
> end kpoints
>
> Then, I re-did the DFT calculation with VASP and set NBANDS to 96 to
> interface with WANNIER90. In the wannierizaion step, I only changed
> num_bands flag from 112 to 96 and kept all other parameter settings the
> same; however, the calculation failed. The wannier90.wout file has the
> following information at the end.
>
> Error at k-point 1 ndimwin 76 num_wann 80
> Exiting.......
> dis_windows: Energy window contains fewer states than number of target WFs
>
> I do not understand why it is that. I suppose that if the num_bands flag
> with 112 in the previous calculation could be done successfully;
> then, num_bands flag with 96 in this new calculation should be done
> successfully as well because the dis_win_max flag in these two calculations
> always remained 150.0.
>
> Would anyone please give me some suggestions/comment on this issue? Thank
> you very much.
>
> Kind regards,
>
> Kenan Song
> Post Doctor in KAUST
>
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