[CP2K-user] [CP2K:21661] Re: SCF convergence

[Frederick Stein]

Dear Sihem,
I would first try to reduce the mixing by adding
&MIXING
  # Lower values improve convergence but increase the number of SCF 
iterations
  # Difficult systems may require even lower values
  ALPHA 0.01
&END
to your SCF section. You can also try different mixing schemes (see 
here: https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/SCF/MIXING.html 
). Unfortunately, there is no standard recipe with difficult to converge 
systems.
HTH,
Frederick

Sihem AZIZI schrieb am Mittwoch, 16. Juli 2025 um 12:35:59 UTC+2:

> Dear Johann,
>
> Thanks a lot for your response.
> I started a new job with the file attached. I paid attention to your 
> comments, but I still get the same warning.
> *** WARNING in qs-scf.F:542 :: SCF run NOT converged ***
> I reduced the number of Ru atoms to reduce the calculation time, and now I 
> don't know whether to stop the calculation or let it continue. Can you tell 
> me what's wrong? Thanks.  ,
> Sihem
>
> On Thursday, July 10, 2025 at 5:38:21 PM UTC+1 Johann Pototschnig wrote:
>
>> Your SCF shows convergence, but doesn't reach the threshold. 
>> It might be sufficient to increase the number of iterations: MAX_SCF 200
>>
>> Otherwise you could try different convergence accelerators. 
>>
>> https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/SCF.html#CP2K_INPUT.FORCE_EVAL.DFT.SCF
>>
>> For a geometry optimization you should increase the SCF 
>> threshold: EPS_SCF 1.0E-6
>> otherwise the gradients will be unreliable. 
>>
>> You have a lot of Ru atoms, but only add 10 orbitals in the Fermi 
>> smearing, which might also cause problems in the SCF convergence. 
>>
>> VdW correction are described in:
>>
>> https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/XC/VDW_POTENTIAL.html
>>
>> On Wednesday, July 9, 2025 at 8:18:18 PM UTC+2 Sihem AZIZI wrote:
>>
>>> Dear all,
>>>
>>> I ran a geometry optimization calculation for a 3-layer Ru slab. The 
>>> calculation ended with the following warning:
>>>  *** WARNING in qs_scf.F:542 :: SCF run NOT converged ***
>>> I have attached the input and the output files.
>>> Also, I would like to know how to add the dispersion and contribution 
>>> of the VDW forces.
>>> Thanks a lot in advance for your help
>>>
>>

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