[CP2K-user] [CP2K:21968] Re: SCF not converging in CaF₂ slab geometry optimisation — advice needed

[Marcella Iannuzzi]

Hi 
The convergence is slow but not too bad 
Increasing the number of MAX_SCF should help.
It is not a good idea to let the geometry optimisation go on with not 
converged SCF, the forces might be very wrong. 

Regards
Marcella


On Saturday, November 15, 2025 at 3:05:00 PM UTC+1 hamidzabihi... at gmail.com 
wrote:

> Hi everyone,
> I am trying to optimise a CaF₂ slab with the bottom layer fixed, but the 
> SCF is not converging. It reaches 250 inner iterations and stops with:
> *** WARNING in qs_scf.F:576 :: SCF run NOT converged ***
> Example of the last SCF steps: 
>
> 243–250 Broy./Diag. ... Total energy ~ -9152.002
>
> Charge densities look fine (total ~ −4.7E-06), but the SCF oscillates and 
> never stabilises.
>
> I’ve attached my input file, log, and the slab .xyz coordinates.
>
> I’d appreciate any suggestions on:
>
>    - 
>    
>    SCF stabilisation (mixing, DIIS, level shifting, smearing, SCF_GUESS, 
>    extrapolation)
>    - 
>    
>    Whether fixing the bottom layer may destabilise SCF
>    - 
>    
>    Better basis/pseudopotential choices for Ca/F slabs
>    - 
>    
>    Recommended cutoffs or other practical tricks for slab systems
>    
> Thanks for any guidance!
>
>
>

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