[CP2K:1819] Re: Example input

[Ondrej Marsalek]

Hi again,

so far, I have only tested a short run of a neat 32 water cluster and
it blew up after about 1.5 ps. I have used

        &LANGEVIN
            GAMMA       [fs^-1] 1.0E-2
            NOISY_GAMMA [fs^-1] 9.0E-5
        &END LANGEVIN

I will try to use a better equilibrated initial condition and tweak
the setup. If I am not able to make it work, I'll post more details
and some specific questions.

I also have one question about the paper

Thomas D. Kuhne and Matthias Krack and Michele Parrinello:
Static and Dynamical Properties of Liquid Water from First Principles
by a Novel Car−Parrinello-like Approach

It says "... we perform a preliminary run in which we vary gamma_D on
the fly...". Is there a way to do that in CP2K or was it done "by
hand"?

Thanks,
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
> >
>