FIST bug?

[Matt W]

Hi Guys,

I've just had a very quick look and I think it is a PME bug. Not SPME,
not QS. Particularly, the QS RS grids are pretty well tested.

If I change the EWALD section to

      &EWALD
        EWALD_TYPE spme
        ALPHA .44
        NS_MAX 25
        GMAX 64 64 64
      &END EWALD

then there is no problem with 8,16 32 procs. All give the same energy

out_spme_8.out: ENERGY| Total FORCE_EVAL ( FIST ) energy (a.u.):
-0.000148559882818
out_spme_16.out: ENERGY| Total FORCE_EVAL ( FIST ) energy
(a.u.):       -0.000148559882818
out_spme_32.out: ENERGY| Total FORCE_EVAL ( FIST ) energy
(a.u.):       -0.000148559882818

I believe that the PME uses a second smaller grid for some purposes -
I would guess that there is some inconsistency in the treatment of the
larger and smaller grids.  I'll try and have a proper look but people
who know the PME code might spot it more quickly.

In summary: there is a bug with PME and at least some distributed
grids. But no evidence for problems with other methods.

Cheers,

Matt

(previous mail to the group got bounced so reposting via google gui)

On Apr 20, 6:00 am, Teodoro Laino <teodor... at gmail.com> wrote:
> 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
>
> > --
> > You received this message because you are subscribed to the Google Groups "cp2k" group.
> > To post to this group, send email to cp... at googlegroups.com.
> > To unsubscribe from this group, send email to cp2k+uns... at googlegroups.com.
> > For more options, visit this group athttp://groups.google.com/group/cp2k?hl=en.
>
> > <out.2><out.16><water_3_dist.inp>