[CP2K-user] [CP2K:17258] Transition metal oxide SCF Convergence

['Börries von Seggern' via cp2k]

Hey, 
Thanks a lot for your help!
Unfortunately, the issue persists. :/ 
Do you have any other ideas of what could be going wrong?
Please find some outputfiles attached.
Kind regards,

Börries

nwi... at berkeley.edu schrieb am Dienstag, 21. Juni 2022 um 18:03:32 UTC+2:

> Some suggestions for what to try:
>
> (1) Precision
>  Your value of EPS_PGF_ORB is too large and should be substantially 
> decreased. I think the default value is too large for a lot of systems. 
> Most numerical issues stem from the overlap matrix precision in my opinion. 
> Set it to something like 1e-16 and see what happens. That might be too 
> fine, but its not very much extra computational cost and it can make a huge 
> difference.
>
> (2) Try these settings
>
> &OT
>  algorithm irac # do not enforce strict orthogonality
>  minimizer cg # safer than DIIS, though often its too safe and makes the 
> calculation slow.
>  linesearch 2pnt # 3pnt is not compatible with irac+rotation
>  rotation true # allow for subspace rotations (fractional occupations)
>  preconditioner full_single_inverse # full_all not compatible with 
> rotations
> &end
>
> If that doesn't work, decrease STEPSIZE in &OT to be 0.05 
>
> Hope that helps,
> Nick
>
> On Tue, Jun 21, 2022 at 8:45 AM 'Börries von Seggern' via cp2k <
> cp... at googlegroups.com> wrote:
>
>> Dear Cp2k Forum,
>> For a while now, I have been trying to calculate XAS Spectra of 
>> transition metal oxides using the LR-TDDFT method. Unfortunately, I wasn`t 
>> able to make the preceeding Hybrid-DFT  SCF calculation converge for 
>> open-shell systems (CuO, CoO, NiO), while other closed shell systems (MgO, 
>> ZnO) show rapid convergence quite easily. So far, I've tried using the OT 
>> methods, which do seem to converge until reaching a sort of plateau, where 
>> the energy starts increasing in miniscule amounts. Further, Iǜe been trying 
>> to use diaganolization, however these calculations seem to oscillate even 
>> when including very little amounts (1e-2) of the new density.
>> Concerning the OT methods, I ve tried both DIIS and CG (with 2pnt and 
>> 3pnt linesearch), however, all calculations show the same behaviour.
>> Could anyone please help me with these calculations?
>>
>> Best regards,
>>
>> Börries
>>
>> PS: Please find an example input, output and structure files attached, I 
>> am using cp2k - 8.2. As even this calculation using the CG optimizer with 
>> linesearch 3pnt reached the plateau and was very expensive, I unfortunately 
>> cancelled the calculation. (But could restart it if necessary) 
>>
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>>
>

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