[CP2K:3205] FIST bug?

[Teodoro Laino]

Hi Noam,

I can confirm your bug report. The issue is related to the relatively new distribution RS_GRID (a couple of years old..).
This means that the same issue could be present also in QS jobs (they share the same infrastructure).

Matt who worked on this stuff is in CC. The issue can be reproduced with this simple input file:

&FORCE_EVAL
  METHOD FIST
  &MM
    &FORCEFIELD
      parm_file_name water.pot  ! (just use the one in tests/Fist/sample_pot/)
      parmtype CHM
      &CHARGE
        ATOM OT
        CHARGE -0.8476
      &END CHARGE
      &CHARGE
        ATOM HT
        CHARGE 0.4238
      &END CHARGE
    &END FORCEFIELD
    &POISSON
      &EWALD
        EWALD_TYPE pme
        ALPHA .44
        NS_MAX 25
      &END EWALD
    &END POISSON
  &END MM
  &SUBSYS
    &CELL
      ABC 24.955 24.955 24.955
    &END CELL
    &COORD
OT   -0.757  -5.616  -7.101    MOL1 
HT   -1.206  -5.714  -6.262    MOL1 
HT    0.024  -5.102  -6.896    MOL1 
OT  -11.317  -2.629  -9.689    MOL2 
HT  -11.021  -3.080 -10.480    MOL2 
HT  -10.511  -2.355  -9.252    MOL2 
    &END
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT water_3_dist
  RUN_TYPE ENERGY_FORCE
&END GLOBAL


If the poisson section is substituted with this one:

    &POISSON
      &EWALD
        EWALD_TYPE pme
        ALPHA .44
        NS_MAX 25
        &RS_GRID
         DISTRIBUTION_TYPE REPLICATED
        &END
      &END EWALD
    &END POISSON

where the distribution_type is set to replicated the bug disappears. So it is triggered by a certain combination of grid points and by the distributed type (which automatically is activated for 16 procs - 2..8 procs instead have replicated type).
All module which use RS_GRID (FIST is just one)  may be affected by this bug, including QS.

Regards,
Teo

On Apr 19, 2011, at 3:37 PM, Noam Bernstein wrote:

> We were playing around with the regtests, specifically
>   cp2k/tests/QMMM/QS/regtest-3/water_3_dist.inp
> On the latest version (cvs update today 19 April), no patches, I get
> different results running on n_proc=2..8 and n_proc=16.  The
> difference seems to happen when RS_GRID goes from fully replicated
> to distributed.  I've attached the input files and two sample output
> files (I changed from QMMM to FIST).  The first output quantity difference
> is on the
>    ENERGY| Total FORCE_EVAL ( FIST ) energy (a.u.):
> energies are off by 8 mRy.  Can someone replicate this issue (I suppose
> I could have compiler or MPI issues, although we think we see this error
> on several somewhat different Linux platforms)?  If so, any ideas
> as to the source of the problem?
> 
>     thanks,
>     Noam
> 
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> <out.2><out.16><water_3_dist.inp>