[gmx-users] system explodes

[Andrea Muntean]

I am simulating one chain of PS. The box is produced by pdb2gmx. If I
run simulations with timestep 0.1 fs up to 0.4 fs everything seem to
be ok. With 1 fs (which should be a normal time for my system) I would
get the following warning:

Warning: 1-4 interaction between 290 and 299 at distance 108.224 which
is larger than the 1-4 table size 1.000 nm
These are ignored for the rest of the simulation
This usually means your system is exploding,
if not, you should increase table-extension in your mdp file

The parameters I use are the following:

title                    = PS
cpp                      = /lib/cpp
integrator               = md
dt                       = 0.0001        ; ps !
nsteps                   = 10000         ; total 10 ps
nstlist                  = 10
nstxout                  = 100
nstvout                  = 100
nstenergy                = 100
unconstrained-start      = yes
nstxtcout                = 50
nstlog                   = 50
constraints              = none
ns_type                  = grid
vdwtype                  = Cut-off
fourierspacing           = 0.055 ; Lbox/0.055 ~ 50
rlist                    = 0.9
rvdw                     = 1.2
tc_grps                  = system
tcoupl                   = berendsen
tau_t                    = 0.1
ref_t                    = 540
Pcoupl                   = no
optimize_fft             = yes

the rest is set default

Did I miss something? What goes wrong?

Any help and/or comments are really appreciated.

Thank you!

Andrea