[Pw_forum] c_bands: eigenvalues not converged (GIPAW)

Jarkko Vähäkangas Jarkko.Vahakangas at oulu.fi
Tue Jan 29 10:15:35 CET 2013

Hi Emine and all.

One thing i do to understand if it is something about gipaw.x or pw.x, is to increase the threshold to the same of the gipaw calculation, (1d-14 in your case) in the pw run and see if one is really in the "noise range" of the calculation due to cutoffs/pseudos/XC.
Works well for me, especially for small systems.

Thanks for advice E. I tried  to increase PW's conv_thr to 1d-14 and luckily i was able to reach that particular convergence after adding of extra bands and change of mixing_mode for my small gap system (17 atoms). Then I launched the gipaw.x module and g-tensor...

Possible reasons of this warning has been discussed many, many times in this forum so i will skip.
But if it is a GIPAW specific problem, for example if the pw calculation is done with a setting that GIPAW doesnt understand therefore cannot solve the correct hamiltonian the wavefunctions are read for, (I think this was happening for the isolated system corrections like martyna-tuckermann )
then please write again and we can discuss more in detail.

and during the magnetic susceptibility calc. the only attentions were following:

 k-point #    3 of    20      pool #  1
     ATTENTION: ik=   3  ibnd= 63  eigenvalues differ too much!
         5.0101      4.7121
     ATTENTION: ik=   3  ibnd= 64  eigenvalues differ too much!
 k-point #    4 of    20      pool #  1

I do not believe that this could be a pw calculation error because similar input for system which contains wider gap works smoothly. What is a good thing is that now i do not get any error of c_band convergence. But should I be worry about ibnd attentions?

Gipaw's ethr is 1d-14 as a default. Can that be reduced and does it make any sense?

Thanks again & BR,


Jarkko Vähäkangas (Ph.D. cand.)
Department of Physics, NMR-group, University of Oulu,
P.O.Box 3000,

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