Re: [Wannier] Enquiry about the Failure in Wannierization Calculation

hoangminh nguyenduy Thu, 01 Apr 2021 07:07:09 -0700

Dear Kenan,

Although 150 >> 15, would you mind checking whether the highest level when num_bands=96 is still higher than the dis_froz_max value?

If the value of dis_froz_max is fine, may you try decreasing the value of dis_win_max so that it is just above the 96^th band?

Best,

Minh.

From: Kenan Song
Sent: Thursday, April 1, 2021 6:03 PM
To: Stepan Tsirkin
Cc: wannier@lists.quantum-espresso.org
Subject: Re: [Wannier] Enquiry about the Failure in Wannierization Calculation

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 <tsirki...@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
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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Re: [Wannier] Enquiry about the Failure in Wannierization Calculation

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