David van der Spoel wrote:
Justin A. Lemkul wrote:


Berk Hess wrote:
Hi,

I don't really know what could be the problem here.

0..180 is (confusingly) not including the end, so 180 is out of range.

The only thing I can think of (except for unknown bugs of coarse),
is that I corrected the coupling time of the Parrinello-Rahman barostat
when going from 4.0 RC4 to the official 4.0 release.
I guess all your old simulations were with older Gromacs releases.
So to get the same coupling as before, so would need to multiply tau_t by 16.6.
I don't know if this would help.

I did see this same error under RC2, but noticed that you fixed this bug shortly after I saw it, and that's what I assumed it was. But now I have seen it under the official 4.0 release.


You did not get pressure coupling warnings before the crash?


There are no messages printed before this error pops up. What's really confusing is that if I simply try the same .tpr file again, it runs without a problem. I know that's not terribly scientific, but it seemed odd to me that my systems running for 40+ ns suddenly had a problem.

Is there any diagnostic information I can provide? This problem seems like it would be elusive, since even I can't fully reproduce it.

That sounds like hardware problems, unless you use dynamic load balancing which depends on timings and hence may make runs irreproducible.


That might be it then. I use -dlb auto, and in the mdrun output to the logfile, it reports that it is turning on dynamic load balancing. Is there any way to diagnose this, i.e. -dlb no? Or is this a problem I'm stuck with based on my hardware?

-Justin


-Justin

Berk


------------------------------------------------------------------------
 > Date: Mon, 13 Oct 2008 16:55:20 -0400
 > From: [EMAIL PROTECTED]
 > To: [email protected]
 > Subject: [gmx-users] Unexplained crashes with Gromacs-4.0
 >
 >
 > Hi,
 >
> I've gotten the following error with two of my simulation systems. Usually this > weird "variable ci" error means the system is unstable, and I've seen it before > when I've done a poor job of equilibrating. But now I'm seeing it a long time > into my simulations (after 48 ns in one case, 60 ns in the other). If I simply
 > re-submit the job, it runs fine. The error shown is as follows:
 >
 > -------------------------------------------------------
 > Program mdrun_4.0_mpi, VERSION 4.0
 > Source code file: nsgrid.c, line: 357
 >
 > Range checking error:
> Explanation: During neighborsearching, we assign each particle to a grid > based on its coordinates. If your system contains collisions or parameter > errors that give particles very high velocities you might end up with some > coordinates being +-Infinity or NaN (not-a-number). Obviously, we cannot
 > put these on a grid, so this is usually where we detect those errors.
> Make sure your system is properly energy-minimized and that the potential
 > energy seems reasonable before trying again.
 >
 > Variable ci has value 180. It should have been within [ 0 .. 180 ]
 >
 > -------------------------------------------------------
 >
> It seems to me that this "ci" variable is still within the range of 0->180, if
 > those values are inclusive.
 >
 > My .mdp file is as follows:
 >
 > title = NPT simulation for a membrane protein
 > ; Run parameters
 > integrator = md
 > dt = 0.002
 > nsteps = 5000000 ; 10000 ps (10 ns)
 > tinit = 40000
 > nstcomm = 1
 > ; Output parameters
 > nstxout = 50000 ; every 100 ps
 > nstvout = 50000
 > nstfout = 50000
 > nstlog = 5000 ; every 10 ps
 > nstenergy = 5000
 > nstxtcout = 5000
 > ; Bond parameters
 > constraint_algorithm = lincs
 > constraints = all-bonds
 > continuation = yes
 > ; Cut-off's and neighborsearching
 > nstlist = 5
 > ns_type = grid
 > rlist = 1.2
 > rcoulomb = 1.2
 > rvdw = 1.2
 > ; PME electrostatics parameters
 > coulombtype = PME
 > fourierspacing = 0.18
 > ;fourier_nx = 0
 > ;fourier_ny = 0
 > ;fourier_nz = 0
 > pme_order = 4
 > ewald_rtol = 1e-5
 > optimize_fft = yes
 > ; Berendsen temperature coupling is on in three groups
 > Tcoupl = Nose-Hoover
 > tc_grps = Protein POPC SOL_NA+_CL-
 > tau_t = 0.1 0.1 0.1
 > ref_t = 310 310 310
 > ; Pressure coupling is not on
 > Pcoupl = Parrinello-Rahman
 > pcoupltype = semiisotropic
 > tau_p = 2.0
 > compressibility = 4.5e-5 4.5e-5
 > ref_p = 1.0 1.0
 > ; Generate velocities is off
 > gen_vel = no
 > gen_temp = 310
 > gen_seed = 7041776
 > ; Periodic boundary conditions are on in all directions
 > pbc = xyz
 > ; Long-range dispersion correction
 > DispCorr = EnerPres
 >
 > Any ideas what's going on?
 >
 > Thanks,
 > Justin
 >
 > --
 > ========================================
 >
 > Justin A. Lemkul
 > Graduate Research Assistant
 > Department of Biochemistry
 > Virginia Tech
 > Blacksburg, VA
 > jalemkul[at]vt.edu | (540) 231-9080
 > http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin
 >
 > ========================================
 > _______________________________________________
 > gmx-users mailing list [email protected]
 > http://www.gromacs.org/mailman/listinfo/gmx-users
> Please search the archive at http://www.gromacs.org/search before posting!
 > Please don't post (un)subscribe requests to the list. Use the
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--
========================================

Justin A. Lemkul
Graduate Research Assistant
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

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