[gmx-users] Energy minimization problem(1-4 interaction at distance 3.540 is larger than the 1-4 table size 1.000 nm)

Arun kumar arun.target at gmail.com
Fri May 4 13:00:24 CEST 2007

Dear gmx-users:
                        I am trying to simulate a surfactant-water
system(also contains some co-surfactants).  Surfactant is a cationic
surfactant with chloride as counterion. And the cosurfactant is fatty
alcohol. water is of spc model. I got topologies from Prodrg for my
surfactant and cosurfactant.  So  I  minimized the energies  for both my
molecules. And prepared a system of 1400 waters, 20 surfactants, 20 counter
ions and 40 cosurfactants in a box  of 5X5X8 nm^3 using packmol.

                       I tried to minimize the energy of the system using
l-bfgs. But I am always getting the error attached below. In my em.mdp file
I am using pme for coulomb type.  Even for MDRUN also I am getting the same
error...  I checked the previous posts and I am unable to understand what's
the problem. And can anyone tell what is meant by broken topology??? Also
try to help me to get out of the problem.

Low-Memory BFGS Minimizer:
   Tolerance (Fmax)   =  2.00000e+04
   Number of steps    =        10000
Warning: 1-4 interaction between 1 and 4 at distance 3.540 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
Using 10 BFGS correction steps.

   F-max             =          inf on atom 97
   F-Norm            =          nan

My topology contains a system of four types surfactant, cosurfctant, water
and Chloride ions. Until grompp everything is fine. Total charge on system
is zero. I can give any more details if it is needed.

Arun kumar.V
M.E Chemical
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