Example input

[Matthias Krack]

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