Dear Kenan,

It seems you may be confusing the "num_wann" and "num_bands" inputs. From the manual:

- "num_bands" is "Number of bands passed to the code"

- "num_wann" is "Number of WF"

In other words, "num_bands" are the bands

*before*disentanglement, and "num_wann" the number*after*disentanglement. Importantly, the number of bands that need to lie within the energy window is "num_wann", not "num_bands".The way I understand the error message is this: Of the 96 bands that

*are*passed to the code, there are fewer than "num_wann" inside the given energy window. Increasing "num_bands" can fix this because more bands are passed to Wannier90 to begin with. As an extreme example, if "num_wann" > "num_bands", the calculation will never work regardless of energy windows.In general, "num_bands" should be the same as the number of bands produced by the first-principles code, minus the number of "exclude_bands". I'm not sure exactly what happens when this is not the case, but maybe it is silently ignored in your case.

Best regards,

Dominik

---

Dominik Gresch

Simulation Engineer

Microsoft Quantum

Date: Thu, 1 Apr 2021 17:58:37 +0300

From: Kenan Song <kenan.s...@kaust.edu.sa>

To: hoangminh nguyenduy <nguyenduyhoangm...@gmail.com>

Cc: "wannier@lists.quantum-espresso.org"

<wannier@lists.quantum-espresso.org>

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

Calculation

Message-ID:

<CAMbJXZ9w6u-bcg7B5YkymnwTYUL8tive=xHYpZurj=c9ad6...@mail.gmail.com>

Content-Type: text/plain; charset="utf-8"

Dear Hoangminh,

Thank you for the suggestion.

I will check that and change the energy window value, as you suggest.

On the other hand, I really do not understand why this problem happened. I

did the wannierization two times. First time, I set num_bands = 112 and

dis_win_max = 150.0; then, the calculation could be done successfully. I

think that this means that 150 eV includes more bands than 112 bands;

otherwise, the calculation would report the error message (dis_windows:

Energy window contains fewer states than number of target WFs).

Second time, I only changed num_bands parameter to 96 and other parameters

remained the same. I suppose that 150 eV should also include far more bands

than 96 bands. Would you please provide me some possible reasons why the

calculation failed, saying 'dis_windows: Energy window contains fewer

states than number of target WFs'?

Thank you very much again.

Kind regards,

Kenan Song

Post Doctor in KAUST

On Thu, Apr 1, 2021 at 5:06 PM hoangminh nguyenduy <

nguyenduyhoangm...@gmail.com> wrote:

> 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 96th band?

>

>

>

> Best,

>

> Minh.

>

> *From: *Kenan Song <kenan.s...@kaust.edu.sa>

> *Sent: *Thursday, April 1, 2021 6:03 PM

> *To: *Stepan Tsirkin <tsirki...@gmail.com>

> *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

> <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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