[CP2K-user] Orbital transformations for system with shallow defect states

[Marcella Iannuzzi]

Dear Nick,

It depends on the system. 
If you expect localised defect states, it might be that DFT is not able to 
find the right state.
You can try to bias at the initial guess the localisation and hope that the 
SCF falls in the right minimum. 
Using OT you can help the SCF convergence by tuning the preconditioner.
If the system is really metallic, you better give up OT.

Regards
Marcella


On Monday, February 15, 2021 at 11:42:01 PM UTC+1 n... at berkeley.edu wrote:

> Hello all,
>
> I am running some defect calculations for vacancies using CP2K, and some 
> of my calculations induce states very close to the band edge. 
>
> I believe this is causing the OT method to be very slow in its 
> convergence, since OT requires (to my knowledge) a clear delineation 
> between occupied/unoccupied states. I would like to continue using OT 
> because of its good scaling behavior, so I'm wondering if there are any 
> tricks to help converge systems with shallow states, or if I simply need to 
> let the SCF proceed for a very long time.
>
> Any suggestions would be appreciated, thanks.
>
> -Nick
>
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