[QE-users] Question on using bands.x with nspin=2 and total_magnetization=1

Sat Sep 6 18:19:42 CEST 2025

Dear Pietro,
I am sorry for my late response as I was out and had limited access to the
internet. Thank you very much for your response. I tried to use
total_magnetization for the scf and for the following nscf and bands, I
removed that. However, as you suspected the error remains.

I understand that you might fix it if I send you the xml file but I need to
run several systems and am looking for a solution. Is there any way you can
guide me to remove the error by myself? I can also send you the xml if you
kindly fix it and let me know the steps.

Thanks you
Rameswar

On Wed, Sep 3, 2025 at 10:50 AM Pietro Davide Delugas <pdelugas at sissa.it>
wrote:

> dear Rameswar
> The bands program is usually called after a pw run with
> calculation='bands'. This is a non-self-consistent calculation, so it is
> not necessary to specify the total magnetisation constraint in its input.
> pw reads the density, initialises the KS Hamiltonian and computes the
> eigenvalues. Removing total magnetisation will likely avoid the error.
> It might be, though, that the two Fermi levels are still reported in the
> XML file, and this may cause the bands to fail.
> in that case just send me the XML file, I will try to fix it manually.
> For the future, we will look into bands to see the reason for this block
> and remove it.
> pietro
> ------------------------------
> *From:* users <users-bounces at lists.quantum-espresso.org> on behalf of
> Rameswar Bhattacharjee <rb1820 at georgetown.edu>
> *Sent:* Wednesday, September 3, 2025 16:33
> *To:* Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
> *Subject:* Re: [QE-users] Question on using bands.x with nspin=2 and
> total_magnetization=1
>
>
> Dear QE community,
>
> I would greatly appreciate your advice on this. Basically, I am trying to
> perform a band structure calculation for a unit cell that contains an
> unpaired electron and is therefore paramagnetic. Could you please suggest
> the proper way to handle this setup?
>
> Thank you for your guidance.
>
> Best regards,
>
> On Sun, Aug 31, 2025 at 5:03 PM Rameswar Bhattacharjee <
> rb1820 at georgetown.edu> wrote:
>
> Dear Dr Paulatto,
> Thank you very much for your response. Actually, the error I am getting is
> as below'
>
> ---------------------------------------------------------
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>      Error in routine bands (1):
>     The bands code with constrained magnetization has not been tested
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> --------------------------------------------------------
>
> And I was wrong earlier, the error also appears even if I do not use
> spin_component. I think this error shows as I have "total_magnetization=1"
> in my scf input.  Now, my system has -2 charge and the spin multiplicity is
> 2.  When I used starting_magnetization instead of total_magnetization, all
> the calculations were fine but I did not get the right magnetic moment as I
> expected.
>
> Basically, I did an scf, nscf, bands and then used a post procession
> calculation using bands.x to generate the ".dat" file for the band
> structure. The first three job competed successfully and the error appears
> only in the last post procession calculation for which the input is below:
>
> ---------------
>
> &BANDS
>
>   prefix = 'crystal_from_cif',
>
>   outdir='./scratch'
>
>   filband = 'bands.dat'
>
> /
> ---------------
>
> I am also attaching the other inputs for you to take a quick look. Please
> note that the coordinates are not complete in the inputs
>
> I am also curious to know about your comment above "It depends on what you
> want to achieve." Could you please elaborate this a bit more?
>
> Your advice would be highly appreciated.
>
> Thanks
> Rameswar
>
> On Sun, Aug 31, 2025 at 3:54 PM Lorenzo Paulatto <lorenzo.paulatto at cnrs.fr>
> wrote:
>
>
>
>    -
>
>    Should I use the spin_component keyword to specify up-spin or
>    down-spin bands, or is it recommended to simply run bands.x without
>    this keyword?
>
> It depends on what you want to achieve.
>
>
>    -
>
>    I tried using spin_component=1 and 2, but I encountered errors in both
>    cases. On the other hand, when I ran bands.x without the spin_component
>     keyword, the job completed normally.
>
> Which error?
>
> Could you please advise on the correct way to handle this situation? Any
> guidance or clarification would be greatly appreciated.
>
> The correct way is to provide the full input and output of the calculation
> that is giving you trouble. And, more in general, if you think that a
> specific output is wrong, you should explain why you think so.
>
> kind regards
>
> Thank you in advance for your help.
>
> Best regards,
> Rameswar Bhattacharjee
>
> --
> Rameswar Bhattacharjee
> Georgetown University
> Washington, DC 20057
>
> _______________________________________________________________________________
> The Quantum ESPRESSO Foundation stands in solidarity with all civilians worldwide who are victims of terrorism, military aggression, and indiscriminate warfare.
> --------------------------------------------------------------------------------
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> users mailing list users at lists.quantum-espresso.orghttps://lists.quantum-espresso.org/mailman/listinfo/users
>
> --
> Dr. Lorenzo Paulatto
> IR IMPMC - CNRS UMR 7590 / Sorbonne Université / MNHN
> phone: +33 (0)1 442 79822 / telegram: lpaulatto
> http://www.impmc.upmc.fr/~paulatto/ - https://anharmonic.github.io/
> 23-24/423 B115, 4 place Jussieu 75252 Paris CX 05
>
> _______________________________________________________________________________
> The Quantum ESPRESSO Foundation stands in solidarity with all civilians
> worldwide who are victims of terrorism, military aggression, and
> indiscriminate warfare.
>
> --------------------------------------------------------------------------------
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users
>
>
>
> --
> Rameswar Bhattacharjee
> Georgetown University
> Washington, DC 20057
>
>
>
> --
> Rameswar Bhattacharjee
> Assistant Research Professor
> Department of Chemistry
> Georgetown University
> Washington, DC 20057
>
> _______________________________________________________________________________
> The Quantum ESPRESSO Foundation stands in solidarity with all civilians
> worldwide who are victims of terrorism, military aggression, and
> indiscriminate warfare.
>
> --------------------------------------------------------------------------------
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users
>

-- 
Rameswar Bhattacharjee
Assistant Research Professor
Department of Chemistry
Georgetown University
Washington, DC 20057
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