[QE-users] Supercell Relaxation for Perovskite compound

[Giovanni Cantele]

Hi,

I tried to run your calculation with the only difference that:
i) qe version il 7.2 instead of 7.3
ii) pseudopotentials are La.pbe-spfn-kjpaw_psl.1.0.0.UPF
 Mn.pbe-spn-kjpaw_psl.0.3.1.UPF  O.pbe-n-kjpaw_psl.1.0.0.UPF

The calculation is running and completed the first scf cycle giving as
output total force 0.004199, pressure -220.25, total energy -6961.50519193,
total magnetization 35.01.
Now, I would exclude that changing the version of qe would transform a
converging calculation into a non converging one. There could be some issue
in your pseudo,
but this is unlikely too, because I did not use pseudos from a
completely different library. So, I'm not sure about what makes difference
between my and your calculation.

By the way, during the calculation I also got suspicious messages saying
that
Minimization algorithm failed to find Fermi energy: reverting to bisection
     Possible cause: smearing is larger than the electronic band-gap.
and which however did not prevent the calculation from converging.

Just to check, i rerun the same run, changing only smearing to 'mv'. This
also gave a converged calculation with total force 0.001821, but in 24
iterations (within the 1st scf cycle) instead of the 45 of the previous run.

So, although I couldn't exactly explain why my calculation is converging
and yours is not, I would suggest changing the smearing.
Also consider that within the UPF file for La I downloaded, the suggested
ecutwfc is 74 Ry, due the fact that La orbital require more plane waves to
be accurately described. So I would certainly make some convergence tests
to see possible differences between 60 Ry (yours) and 74 Ry (suggested).

Giovanni


-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it <giovanni.cantele at spin.cnr.it>
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: https://sites.google.com/view/giovanni-cantele/home


Il giorno ven 25 ott 2024 alle ore 11:22 Hüseyin Yasin Uzunok via users <
users at lists.quantum-espresso.org> ha scritto:

> Dear Users,
> I want to make a VC relaxation for a 2x2x2 supercell of laMno3
> perovskite compound. I tried several approaches. Even though it seems to
> give a reasonable energy value at first, the energy values become
> unacceptable. I couldn't find any obvious error in my input file, so it
> would be nice if you could tell me what I did wrong. Please see the
> attached input and output files.
> Best regards.
>
> Yasin
> Sakarya University
>
>
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