[CP2K-user] [CP2K:12884] OT for Aluminum Oxide?

[Nicholas Winner]

OT should certainly be fast for a large band gap system like Al2O3. You
said that the speed of the scf iterations are slower, but is the full scf
convergence also slower? Things to consider are your preconditioner and
your outer loops I think. Full_single_inverse will be less effective than
Full_all in most situations. Generally use Full_all unless your system is
very large. Maybe also try reducing your max inner SCF cycles and
increasing your outer loop number. It could be that your initial state is
not so good, and so resetting often using more frequent outer loops will
help.

On Sat, Feb 15, 2020, 5:59 AM MD Simulation <mdsimula... at gmail.com>
wrote:

> Does anyone know if the OT method could be used for aluminum oxide
> (Al2O3)?  It seemed a bit slow when I tried it compared to using SMEAR.
>
> Here's my two SCF solving routines, the OT method is slow, ~9s per SCF
> iteration, while the SMEAR method is ~3s per SCF iteration.  Thanks for the
> help.
>
> #### OT
>         &SCF
>             SCF_GUESS ATOMIC
>             EPS_SCF 1.0E-8
>             MAX_SCF 200
>             &OT ON
>                 MINIMIZER DIIS
>                 PRECONDITIONER FULL_SINGLE_INVERSE
>             &END OT
>             &OUTER_SCF
>                 MAX_SCF 10
>                 EPS_SCF 1.0E-8
>             &END OUTER_SCF
>         &END SCF
> ####
>
> #### Fast SMEAR
>         &SCF
>             SCF_GUESS ATOMIC
>             EPS_SCF 1.0E-8
>             MAX_SCF 200
>             ADDED_MOS 10
>             &DIAGONALIZATION ON
>                 ALGORITHM STANDARD
>             &END DIAGONALIZATION
>             &MIXING  .TRUE.
>                 METHOD BROYDEN_MIXING
>                 ALPHA 0.4
>                 NBROYDEN 8
>             &END MIXING
>             &SMEAR ON
>                 METHOD FERMI_DIRAC
>                 ELECTRONIC_TEMPERATURE [K] 300.0
>             &END SMEAR
>         &END SCF
> ####
>
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