[CP2K:1819] Re: Example input

[Ondrej Marsalek]

Dear Matthias,

thank you for the detailed information. In the meantime I have found
and old post at the BerliOS forum, but it was much more brief, so this
is definitely useful. I have also managed to get the relevant cited
papers and will work on this as soon as I get back to my computer. I
may have more questions then, but at the moment I think I understand
it.

I do realize that this is only suitable for longer runs, but that is
exactly the reason I am interested in it.

By the way, the Ricci and Ciccotti paper (Langevin dynamics
propagator) is cited in your PRL paper and is also mentioned in the
source code, maybe it would be a good idea to include it in the
"official" CP2K references.

Best regards,
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
> >
>