[gmx-users] Fatal error: Force field inconsistency

[svb1 at msstate.edu]

Hello,
I had this error while trying to run  a simulation for a small molecule without
water and bilayer, I have included in the topol.top its parameters taken from
OPLS and its topology, since I did not created the topology with the pdb2gmx I
did not included the ffoplsa.itp in the topol, however after grompp -norenum
–debug, and mdrun I got the following message
Fatal error: Force field inconsistency: 1-4 interaction parameters for
atoms 9-10 not the same as for other atoms with the same atom type.
I already checked the [pairs] and found that for the same type of atoms the
parameters are the same . so why is giving me this error?. It doesn't make
sense.
I read in the GROMACS mailing list that including  -norenum with grompp, it make
work but it did not, so what I did was to commented out the 9-10 pair
interaction from [pairs], but still the same error, then I comented out [pairs]
and all the 1-4 interactions defined in [pairs] in my molecule.itp, and after
grompp and mdrun the system did not complain.
The thing is that now it is calculating the 1-4 interactions from the molecule
parameters in molecule.itp [which has the parameters and topology], with :[
defaults ]
; nbfunc        comb-rule       gen-pairs       fudgeLJ fudgeQQ
  1             1               yes             1.0     0.5

because the explicit [pairs ] were comented out due to the Fatal error: Force
field inconsistency.
Can somebody give an advice, some people had this problem posted on the web, but
I couldn't find the solution for my eventhought we all get the same error.
Thanks,
Sandra