[gmx-users] Incorrect number of atomtypes for dihedral (4 instead of 2 or 4)

[Mark Abraham]

fulya caglar wrote:
>   Hi all!
>  I have a protein-protein complex in my simulation so I used the pdb2gmx 
> command 
> for getting the .itp file. 

pdb2gmx generates .top files, technically speaking.

> Then i added the corresponding .itp file in 
> the top file .
> While running the grompp i am getting the following error:
>  
> ERROR 1 [file "drg.itp", line 7]:
>   Incorrect number of atomtypes for dihedral (4 instead of 2 or 4)
> ERROR 2 [file "drg.itp", line 8]:
>   Incorrect number of atomtypes for dihedral (4 instead of 2 or 4)
> ERROR 3 [file "drg.itp", line 9]:
>   Incorrect number of atomtypes for dihedral (4 instead of 2 or 
> 4)..............
>  
> But when I checked the .itp file it is exactly same the .itp file of my 
> successful simulations of the ligand protein.
> I would be very grateful to know why I get this type of error and what 
> can I do about this.  Thanks very much.

Last time I saw something like this it was the dihedral type changing 
from one setting to another (or to or from a default). Check chapter 
five and the first section of your .top files. Do let me know what the 
problem was and I'll FAQ it for the Wiki.

Mark