[gmx-users] Incorrect number of atomtypes for dihedral

Debashis Sahu debashis.sahu87 at gmail.com
Fri Jul 20 20:00:45 CEST 2012

Dear all

          I used Gromacs 4.5 for thio-Urea molecule  in OPLS-AA force
field, but in grompp step I got an error as follows:


Back Off! I just backed up mdout.mdp to ./#mdout.mdp.4#

checking input for internal consistency...

processing topology...

ERROR 1 [file ffbonded.itp, line 2634]:

  Incorrect number of atomtypes for dihedral (4 instead of 2 or 4)

ERROR 2 [file ffbonded.itp, line 2636]:

  Incorrect number of atomtypes for dihedral (4 instead of 2 or 4)

Generated 332520 of the 332520 non-bonded parameter combinations

Generating 1-4 interactions: fudge = 0.5

Generated 332520 of the 332520 1-4 parameter combinations

Excluding 3 bonded neighbours molecule type 'Other_chain_X'

NOTE 1 [file topol.top, line 94]:

  System has non-zero total charge: -1.000000

  Total charge should normally be an integer. See


  for discussion on how close it should be to an integer.

processing coordinates...

double-checking input for internal consistency...

There was 1 note


Program grompp, VERSION 4.5.5

Source code file: grompp.c, line: 1372

Fatal error:

There were 2 errors in input file(s)

For more information and tips for troubleshooting, please check the GROMACS

website at http://www.gromacs.org/Documentation/Errors

I tried lot of times to change the atom type mention in dihedral but failed.

Can any one help me to recover this?

with best regards..............

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