[gmx-users] grompp error - incorrect number of parameters

[Lara Bunte]

Hello 


After 


grompp -f em.mdp -p topol.top -c solvated.gro -o em.tpr


I got the error:

Incorrect number of parameters - found 2, expected 4 or 4 for U-B.


I thought that this could be an inconsistency be declaring the functions, but in my topology I have function 4 (for improper dihedrals):


Out of topol.top

[ dihedrals ]
;  ai    aj    ak    al funct            c0            c1            c2            c3
    1     8     6     4     4    180   100


And in my .rtp file in the CHARMM27 force field folder I have:

Out of .rtp file
; bonds  angles  dihedrals  impropers
     1       5          4        4


and in my ffbonded.itp file I have:
[ dihedraltypes ]
; i     j       k       l       func    q0      cq
ON1     NN3A      CN1A       NN2U   4   180   100


So in alle three files, ffbonded.itp, topol.top and the .rtp parametrization file I have the function 4 for the improper dihedrals. 


What is the problem?

Thanks for helping me
Greetings
Lara