[Wannier] Enquiry about the Failure in Wannierization Calculation

Sat Apr 3 09:44:10 CEST 2021

Dear Dominik,

Thank you very much for the explanation and suggestion.

I will try more num_bands. Thank you again.

Kind regards,

Kenan Song
Post Doctor in KAUST

On Thursday, April 1, 2021, Dominik Gresch <greschd at gmx.ch> wrote:

> 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.song at kaust.edu.sa>
> To: hoangminh nguyenduy <nguyenduyhoangminh at gmail.com>
> Cc: "wannier at lists.quantum-espresso.org"
> <wannier at lists.quantum-espresso.org>
> Subject: Re: [Wannier] Enquiry about the Failure in Wannierization
> Calculation
> Message-ID:
> <CAMbJXZ9w6u-bcg7B5YkymnwTYUL8tive=xHYpZurj=C9aD6PYA at 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 <
> nguyenduyhoangminh at 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.song at kaust.edu.sa>
> > *Sent: *Thursday, April 1, 2021 6:03 PM
> > *To: *Stepan Tsirkin <tsirkinss at gmail.com>
> > *Cc: *wannier at 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 <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!gqlLXswbnFUpi5njS6jJ3Udm9LOYzaTQ9gagQUarlBQ0thT3H_yZuHc2JNEEydWv5plF$>
> > <https://urldefense.com/v3/__http:/wannier-berri.org__;!!Nmw4Hv0!
> mcRhIZFtkkQwIAT8TyKbCdjzSk8IetfWcmjwpRZp-udWAbKcLoQ1Q9Vamt-4HoG-iizG$>
> >
> > 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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