[gmx-users] "Range checking error" issue

[Matteo Guglielmi]

Hello world,

the following is my input file:

########
title                    = 2masn
cpp                      = /usr/bin/cpp
define                   = -DPOSRES
integrator               = md
tinit                    = 0
dt                       = 0.002
nsteps                   = 1500000
init_step                = 0
comm_mode                = Angular
nstcomm                  = 1
comm_grps                = Pore
nstxout                  = 250000
nstvout                  = 250000
nstfout                  = 250000
nstcheckpoint            = 1000
nstlog                   = 2500
nstxtcout                = 2500
xtc_grps                 = System
energygrps               = Pore Membrane Ions Water
nstenergy                = 2500
nstlist                  = 5
ns_type                  = grid
pbc                      = xyz
rlist                    = 1.0
coulombtype              = PME
rcoulomb                 = 1.0
vdwtype                  = Cut-off
rvdw                     = 1.4
fourier_nx               = 88
fourier_ny               = 88
fourier_nz               = 88
pme_order                = 4
ewald_rtol               = 1e-5
ewald_geometry           = 3d
optimize_fft             = yes
tcoupl                   = berendsen
tc_grps                  = Solute Solvent
tau_t                    = 0.1    0.4
ref_t                    = 300    300
pcoupl                   = berendsen
pcoupltype               = anisotropic
tau_p                    = 0.5      0.5      0.5      0.5    0.5    0.5
compressibility          = 4.53e-5  4.53e-5  4.53e-5  0.0    0.0    0.0
ref_p                    = 1.025    1.025    1.025    1.025  1.025  1.025
gen_vel                  = yes
gen_temp                 = 300
gen_seed                 = 173529
constraints              = all-bonds
constraint_algorithm     = lincs
unconstrained_start      = no
lincs_order              = 4
lincs_iter               = 2
lincs_warnangle          = 30
################

and way after the very beginning of this simulation (~1.5ns) I always
get this error message:

##########
   Rel. Constraint Deviation:  Max    between atoms     RMS
       Before LINCS         0.032676  17797  17799   0.003970
        After LINCS         0.000004  17162  17169   0.000000

Grid: 10 x 11 x 12 cells
Grid: 10 x 12 x 12 cells
Grid: 10 x 11 x 12 cells
Grid: 10 x 12 x 12 cells
Grid: 10 x 11 x 12 cells
Grid: 10 x 12 x 12 cells
Grid: 10 x 11 x 12 cells
Grid: 10 x 12 x 12 cells
Grid: 10 x 11 x 12 cells
-------------------------------------------------------
Program mdrun_mpi, VERSION 3.3.1
Source code file: nsgrid.c, line: 226

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 1434. It should have been within [ 0 .. 1320 ]
Please report this to the mailing list (gmx-users at gromacs.org)
-------------------------------------------------------
#################

Is my input file so bad?

(I've seen people using lincs with 5fs time step...)

Thanks for any useful suggestion,
MG.