[CP2K:1819] Re: Example input

[Ondrej Marsalek]

Hi again,

I am doing some test runs and hopefully making some progress. One thing
does not work as expected, though. I have the following SCF section:

&SCF
    EPS_SCF 1.0E-7
    MAX_SCF 30
    EPS_SCF_HIST 1.0E-4
    SCF_GUESS atomic
    &OT
        MINIMIZER DIIS
        PRECONDITIONER FULL_KINETIC
        STEPSIZE 0.1
    &END OT
    &OUTER_SCF T
        MAX_SCF 50
        EPS_SCF 1.0E-7
    &END OUTER_SCF
    &PRINT
        &RESTART_HISTORY
            ADD_LAST NUMERIC
            BACKUP_COPIES 7
            FILENAME =W32-neat-RESTART_HISTORY.wfn
            &EACH
                __ROOT__ 1
                MD 1
                QS_SCF 0
            &END EACH
        &END RESTART_HISTORY
    &END PRINT
&END SCF

After collecting enough points for the extrapolation, the outer SCF loop
never converges. There is always just one inner SCF iteration (as it
stays below EPS_SCF_HIST all the time) and then the next outer SCF
interation, until the limit of 50 iteration is exceeded. It looks like
the outer SCF is trying to reach its EPS_SCF. When I exchange SCF /
EPS_SCF_HIST for SCF / MAX_SCF_HIST, it works fine.

Thanks for any help,
Ondrej


On Mon, Mar 2, 2009 at 09:51, Matthias Krack <matthia... at psi.ch> wrote:
>
> Dear Ondrej,
>
> you have to select the ENSEMBLE LANGEVIN together with the
> EXTRAPOLATION ASPC (which is now the default). Activate the printing
> of the RESTART_HISTORY to enable a smoother restart of consecutive
> runs. Then you have to find the appropriate gamma values for your
> system. Here is a CP2K input template showing the essential parts
> needed for the setup:
>
> &MOTION
>  &MD
>  ENSEMBLE LANGEVIN
>  &LANGEVIN
>   GAMMA [fs^-1] 1.0E-3 # "Langevin" gamma (adapt for your system)
>   NOISY_GAMMA [fs^-1] 3.0E-5 # dissipative gamma (adapt for your
> system)
>  &END LANGEVIN
>  ...
>  &END MD
> &END MOTION
>
> &FORCE_EVAL
>  METHOD Quickstep
>  ...
>  &DFT
>  WFN_RESTART_FILE_NAME <project>-RESTART_HISTORY.wfn
>  &QS
>   EXTRAPOLATION ASPC
>   EXTRAPOLATION_ORDER 3 # find the best for your system
>   ...
>  &END QS
>  &SCF
>   EPS_SCF 1.0E-7
>   EPS_SCF_HIST 1.0E-5
>   MAX_SCF 40
>   #MAX_SCF_HIST 2 # instead of EPS_SCF_HIST for a fixed number of SCF
> steps
>   SCF_GUESS history_restart
>   ...
>   &OT ON
>    MINIMIZER DIIS
>    PRECONDITIONER FULL_KINETIC # try the cheapest first
>    STEPSIZE 0.1
>   &END OT
>   &OUTER_SCF
>    EPS_SCF 1.0E-7
>    MAX_SCF 50
>   &END OUTER_SCF
>   &PRINT
>    &RESTART_HISTORY
>     ADD_LAST NUMERIC
>     BACKUP_COPIES 5 # ASPC order + 2
>     FILENAME =<project>-RESTART_HISTORY.wfn
>     &EACH
>      __ROOT__ 1
>      MD 1
>      QS_SCF 0
>     &END EACH
>    &END RESTART_HISTORY
>   &END PRINT
>   ...
>  &END SCF
>
> Note, the gamma values are only given to provide some reasonable
> starting values w.r.t. their relative size and the order of magnitude.
> You may select a fixed (very low) number of SCF iteration steps using
> MAX_SCF_HIST or a less tight SCF convergence criterion using
> EPS_SCF_HIST. Please, keep in mind that the procedure only pays back,
> if you are planning long simulation runs, since setup, thermalization
> and the adjustment of the gamma values requires already several ps of
> simulation time.
>
> Best regards,
>
> Matthias
>
>
> On Feb 27, 8:00 pm, Ondrej Marsalek <ondrej.... at gmail.com> wrote:
>> Dear CP2K users,
>>
>> I am interested in the method described in this paper:
>>
>> Thomas D. Kuhne and Matthias Krack and Fawzi R. Mohamed and Michele
>> Parrinello: Efficient and Accurate Car-Parrinello-like Approach to
>> Born-Oppenheimer Molecular Dynamicshttp://link.aps.org/abstract/PRL/v98/e066401
>>
>> Unfortunately, I have trouble mapping the paper to a working
>> computational setup and CP2K input. Would anyone be willing to provide
>> an example?
>>
>> Thank you,
>> Ondrej Marsalek
> >
>