[Pw_forum] problem with convergence during SCF-procedure

[Agostino Migliore]

Hello Alex

Since, you have transition metals in your system, it could help you to
introduce an electronic smearing and then progressively  reduce it until
you get the solution without any orbital fractional occupations.
Then, from the attached file I saw that you are using  mixing_beta =
0.7D0. Did you try something like mixing_beta = 0.5 or similar (perhaps
you already did, but I don’t know) and also mixing_mode = ‘plain’
(although I know that the local_TF mode may be good for highly
inhomogeneous systems).
Finally, your system includes Ti atoms, which have d electrons. Have you
tried to use the Hubbard U correction scheme implemented in pwscf? Also
irrespective of your convergence problem, it could provide you with a
better description of the electronic structure (indeed, I don’t have
direct experience on Ti, but I have on Fe, and the Hubbard U correction
term works well).
I hope something I said can help you.

Best regards,
Agostino Migliore
CMM, Department of Chemistry, Philadelphia


Quoting Alexej Mazheika <alex.mazheika at gmail.com>:

> Dear all
>
> I perform the calculations of surface with adsorbed cluster Ag4/TiO2 and
> have a problem with convergence during SCF-procedure. It does not converge.
> In order to eliminate it I tried the shown methods in the user_guide: to
> decrease mixing beta, to increase mixing ndim, to increase ecutwfc and
> ecutrho. But it didn't help me. Is there any other methods to solve such
> problem? The input file is here attached.
>
> Best regards
> Alex Mazheika, Research Institute for phys. and chem. problems, Minsk,
> Belarus
>