[QE-users] problem with convergence of MnTe altermagnet hexagonal phase

[Alpin Novianus Tatan]

Dear Prof. Marzari,

Thank you for your comments. I agree that if convergence is achieved and
the same physical approximation (e.g., PBE) is used, calculations employing
ultrasoft, PAW, or norm-conserving pseudopotentials should yield the same
physical results.

My previous comment was intended to address a different issue, namely the
practical difficulty of achieving convergence, which Ireneusz encountered.
In practice, the ease of obtaining convergence can differ between
pseudopotential types and computational implementations. For that reason, I
suggested trying different pseudopotential types rather than restricting
the calculations to PAW, since this may improve convergence without
changing the underlying physical approximation.

Best regards,

Alpin N. Tatan
Department of Physics
The University of Tokyo

On Mon, Jul 6, 2026 at 5:37 PM Nicola Marzari <nicola.marzari at epfl.ch>
wrote:

>
>
> Dear all,
>
>
> just a note on these comments below. All codes (all electron,
> pseudopotential PAW, ultrasoft, normconserving) should give the same
> numerical result for a given physical approximation (e.g., PBEsol).
>
> If they do not, there is a problem - this is why verification (in
> "verification and validation") is very important - making sure codes
> give a numerically exact answer to a given physical theory (the theory
> needs to be "validate", i.e. good enough to describe the physics at hand
> - you cannot do DFT PBEsol to study say a Hubbard sideband.
>
> There has been a lot of progress on "verification", as you can see in
> https://www.nature.com/articles/s42254-023-00655-3 , with all-electron
> and pseudopotential codes giving very close restuls.
>
> For QE, there are curated efforts here:
> https://legacy.materialscloud.org/discover/sssp/ - so that's a good
> start, and you can find PBE and PBEsol pseudos tuned for efficiency
> (lower cost) or accuracy (higher cost); we'll release very soon a major
> update with all the data from the paper above.
>
> nicola
>
>
> >     Authors of the paper used VASP but it should be possible in Quantum
> >     Espresso.
> >
> >
> > This is not always the case, do not assume this.
> > Pseudopotentials are an important part of the calculation, which are
> > different sets for VASP and QE.
> > The calculation and the code implementation are also different.
> >
> --
> ----------------------------------------------------------------------
> Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
> Director, National Centre for Competence in Research NCCR MARVEL, SNSF
> Laboratory Head, PSI Center for Scientific Computing, Theory, and Data
> Contact info and websites:  https://theos-wiki.epfl.ch/en/Main/Contact
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20260706/bfeb49fe/attachment.html>