[gmx-users] Incorrect number of parameters - found 2, expected 5 or 5 for LJC-14 q

[Justin A. Lemkul]

Biswajit Gorai wrote:
> Dear GROMACS users,
> 
> I am beginner to GROMACS. I want to simulate my protein in different 
> concentrations of Guanidinium Chloride solution and collected the files 
> (3M & 5M box and .itp file) from 
> http://www.gromacs.org/Downloads/User_contributions/Molecule_topologies. 
> Then I build a topology file 'topol.top' (to minimize the box further) as
> 
> ; Include forcefield parameters
> #include "gromos43a1.ff/forcefield.itp"
> 
> #include "gnd.itp"
> 
> ; Include water topology
> #include "gromos43a1.ff/spc.itp"
> 
> #ifdef POSRES_WATER
> ; Position restraint for each water oxygen
> [ position_restraints ]
> ;  i funct       fcx        fcy        fcz
>    1    1      1000       1000       1000
> #endif
> 
> ; Include topology for ions
> #include "gromos43a1.ff/ions.itp"
> 
> [ system ]
> ; Name
> Gdm 3M
> 
> [ molecules ]
> ; Compound        #mols
> GND 19
> SOL             269
> CL-             19
> 
> Then I execute the command
> $ grompp -f minim.mdp -c gnd3M.gro -p topol.top -o em.tpr
> 
> But I got the following error
> 
> Program grompp, VERSION 4.5.5
> Source code file: toppush.c, line: 1631
> 
> Fatal error:
> Incorrect number of parameters - found 2, expected 5 or 5 for LJC-14 q.
> For more information and tips for troubleshooting, please check the GROMACS
> website at http://www.gromacs.org/Documentation/Errors
> -------------------------------------------------------
> 
> Is there something wrong with the .itp file (given) or I am doing any 
> mistake?
> 

The .itp file is wrong.  With pair type 2, 5 parameters are required (FudgeQQ, 
qi, qj, V, and W), unlike pair type 1, which only requires 2 (V and W).  See 
Table 5.5 in the manual for the required format.

-Justin

-- 
========================================

Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
MILES-IGERT Trainee
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080
http://www.bevanlab.biochem.vt.edu/Pages/Personal/justin

========================================