Setting correct cutoff/convergence criteria

Matt W mattwa... at
Mon Jul 10 17:35:44 UTC 2017

> 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

         EPS_SCF 5.0E-7
         MAX_SCF 1
      EPS_SCF 5.0E-7
      MAX_SCF  15
        ENERGY_GAP 0.001
    &END SCF

would be my default setup. 

        ENERGY_GAP 0.1

for large systems (>500 atoms or so)



> Thanks
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