Setting correct cutoff/convergence criteria

[ashish dabral]

Thanks a lot Matt for your suggestions and additional clarification.

On Monday, 10 July 2017 19:35:44 UTC+2, Matt W wrote:
>
>
>> Thanks for your suggestions. After playing around with the parameters, I 
>> figured the Extrapolation issue and cut-off issue (so fixed that). 
>> I already see improvement in time after some trials. I am wondering 
>> though which method would be best for extrapolation: ASPC etc.
>>
>
> I'd stick with ASPC. PS is maybe a bit faster for geo_opt, but ASPC should 
> be good and robust.
>  
>
>> I haven't switched to GAPW though. I will try that. 
>>
>
> Only needed really when you have some elements that need stupidly large 
> cutoff (F, Na, Mg) with normal pseudos. It does tend to make forces a bit 
> more accurate, so can speed up final convergence a lot too.
>  
>
>> Can you please elaborate on "Mixing and broyden optimizer will be 
>> moderately inefficient for insulators"
>> and a possible alternative.
>>
>> The Orbital Transform (OT) method is CP2Ks flagship optimizer for 
> insulators. For a smallish system
>
>     &SCF
>       &OUTER_SCF
>          EPS_SCF 5.0E-7
>          MAX_SCF 1
>       &END OUTER_SCF
>       SCF_GUESS RESTART
>       EPS_SCF 5.0E-7
>       MAX_SCF  15
>       &OT
>         MINIMIZER DIIS
>         PRECONDITIONER FULL_ALL
>         ENERGY_GAP 0.001
>       &END
>     &END SCF
>
> would be my default setup. 
>
>         PRECONDITIONER FULL_SINGLE_INVERSE
>         ENERGY_GAP 0.1
>
> for large systems (>500 atoms or so)
>
> Matt
>
>  
>
>> Thanks
>>
>>>
>>>>
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