[QE-users] nscf in super cell

[pboulet]

Hello,

The criteria you chose look wierd and overly tight: conv_thr=1e-20 and ecutwfc=200 ecutrho=800. They are unusual parameters for common calculations.

Have you run the examples given with the QE distribution to get acquainted to ab initio techniques? They are helpful when starting ab initio calculations.

Regarding your question, browse the QE mailing-list, as this question as been asked many, many times:
https://www.mail-archive.com/users@lists.quantum-espresso.org/ <https://www.mail-archive.com/users@lists.quantum-espresso.org/>

HTH,

Pascal Boulet
—
Professor in computational materials - DEPARTMENT OF CHEMISTRY
University of Aix-Marseille - Avenue Escadrille Normandie Niemen - F-13013 Marseille - FRANCE
Tél: +33(0)4 13 55 18 10 - Fax : +33(0)4 13 55 18 50
Email : pascal.boulet at univ-amu.fr <mailto:pascal.boulet at univ-amu.fr>



> Le 13 mai 2020 à 21:18, Fariba Islam <ezqhaz at gmail.com> a écrit :
> 
> Dear all,
> My  conv_thr=1e-20 and ecutwfc=200 ecutrho=800
> My nscf calculation is crashing with the error 
> 
> task #        10
>      from c_bands : error #         1
>      too many bands are not converged
> 
> How can I solve ?
> 
> On Tuesday, May 12, 2020, Fariba Islam <ezqhaz at gmail.com <mailto:ezqhaz at gmail.com>> wrote:
> Thanks
> 
> On Tue, May 12, 2020 at 12:41 PM Paolo Giannozzi <p.giannozzi at gmail.com <mailto:p.giannozzi at gmail.com>> wrote:
> On Tue, May 12, 2020 at 7:08 AM Fariba Islam <ezqhaz at gmail.com <mailto:ezqhaz at gmail.com>> wrote:
> I wrote the following code for nscf calculation of a silicon supercell. Why do I get 
> "c_bands:  2 eigenvalues not converged
>  c_bands:  1 eigenvalues not converged...." in my output file and the calculation is not stopping
> 
> if it is not stopping, there is no problem. In a scf calculation, the iterative diagonalization starts from wavefunctions computed at the previous scf step and usually converges quickly. The maximum number of internal iterations is thus small (20 if I remember correctly). In a non-scf calculation, there isn't such a good starting point and iterative diagonalization sometimes does not converge for all eigenvalues in 20 iterations, but it is usually sufficient to repeat the diagonalization.
> 
> Paolo
> 
> &control
>     calculation = 'nscf'
>     restart_mode='from_scratch'
>     prefix = 'si_b'
>     outdir='./tmp/'
>     pseudo_dir='../pseudo/'
> /
> &system
>     ibrav=2, celldm(1) = 20.8218, 
>     nat=16, ntyp=1,
>     ecutwfc=40
>     ecutrho=160
>     noinv=.true.
>     nosym=.true.
>     occupations='smearing' , smearing='gaussian',degauss=0.005
> /
> &electrons
>     conv_thr=1e-8
> /
> ATOMIC_SPECIES
>  Si  28.0855  Si_ONCV_PBE-1.0.upf
> 
> ATOMIC_POSITIONS (alat)
> Si 0.000000   0.000000   0.000000
> Si -0.374989   0.375011   0.375011
> Si -0.250000   0.250000   0.000000
> Si -0.624989   0.625011   0.375011
> Si 0.000000   0.250000   0.250000
> Si -0.374989   0.625011   0.625011
> Si -0.250000   0.500000   0.250000
> Si -0.624989   0.875011   0.625011
> Si -0.250000   0.000000   0.250000
> Si -0.624989   0.375011   0.625011
> Si -0.500000   0.250000   0.250000
> Si -0.874989   0.625011   0.625011
> Si -0.250000   0.250000   0.500000
> Si -0.624989   0.625011   0.875011
> Si -0.500000   0.500000   0.500000
> Si -0.874989   0.875011   0.875011
> 
> K_POINTS {automatic}
> 12 12 12 0 0 0
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso <http://www.max-centre.eu/quantum-espresso>)
> users mailing list users at lists.quantum-espresso.org <mailto:users at lists.quantum-espresso.org>
> https://lists.quantum-espresso.org/mailman/listinfo/users <https://lists.quantum-espresso.org/mailman/listinfo/users>
> 
> -- 
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
> 
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso <http://www.max-centre.eu/quantum-espresso>)
> users mailing list users at lists.quantum-espresso.org <mailto:users at lists.quantum-espresso.org>
> https://lists.quantum-espresso.org/mailman/listinfo/users <https://lists.quantum-espresso.org/mailman/listinfo/users>_______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20200514/f3820964/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 1585 bytes
Desc: not available
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20200514/f3820964/attachment.p7s>