[gmx-users] still about the opls methanol box

[ioannis.nicolis at free.fr]

En réponse à Erik Lindahl <lindahl at stanford.edu>:

> That's normal; by reproducible I mean if the crash happens again if you
> start from exactly the same .tpr file (sorry if that will take a
> while).

OK, I began again from the same initial conditions but recording every 
step and the crash is absolutely reproducible after 221690 steps:

********************************************************
step 221690, will finish at Mon Oct 14 04:58:12 2002Warning: Only triclinic 
boxes with the first vector parallel to the x-axis and the second vector in 
the xy-plane are supported.
         Box (3x3):
            Box[    0]={         NaN,          NaN,          NaN}
            Box[    1]={         NaN,          NaN,          NaN}
            Box[    2]={         NaN,          NaN,          NaN}
         Can not fix pbc.

(repeated 6 times)

Fatal error: ci = -1 should be in 0 .. -1 [FILE nsgrid.c, LINE 210]
**************************************************

I looked at densities, box sizes, temperatures etc.
Everything goes NaN similtaneously at 221.693 but till then they all look 
fine.
I then looked at the energy contributions. There is only one value going 
NaN one step earlier that's LJ(SR) that goes NaN at 221.693 but again it's 
normal till then. All the other energies go NaN at 221.694. Here are the 
different energies from g_energy:

**********************************
@ s0 legend "Bond"
@ s1 legend "Angle"
@ s2 legend "Ryckaert-Bell."
@ s3 legend "LJ (SR)"
@ s4 legend "LJ (LR)"
@ s5 legend "Disper. corr."
@ s6 legend "Coulomb (SR)"
@ s7 legend "Coulomb (LR)"
  221.692017  12193.733398  13178.763672  2376.947266  -
10464.546875  -552.084656  -322.367950  -43431.441406  -
5436.880859
  221.693008  12668.963867  13243.346680  2373.988770         NaN  -
552.084656  -322.354370  -43493.394531  -5440.968750
  221.694016         NaN         NaN         NaN         NaN  -552.084656         
NaN         NaN         NaN
  221.695007         NaN         NaN         NaN         NaN  -552.084656         
NaN         NaN         NaN
  221.696014         NaN         NaN         NaN         NaN  -552.084656         
NaN         NaN         NaN
  221.697006         NaN         NaN         NaN         NaN  -552.084656         
NaN         NaN         NaN
  221.698013         NaN         NaN         NaN         NaN  -552.084656         
NaN         NaN         NaN
  221.699005         NaN         NaN         NaN         NaN  -552.084656         
NaN         NaN         NaN
*************************************************

If I look at the total potential till the crash I have a mean value of  -19.12 
per molecule.
I also looked at the ngmx animation, there is no implosion nor explosion...

Any suggestions?

Thanks a lot,

Yiannis