[gmx-users] Atom Type not found............

Justin A. Lemkul jalemkul at vt.edu
Wed Apr 21 14:02:23 CEST 2010

> HI
>    i have generated a topology file for drug using prodrg with gromos 
> 96.1force field , now i want to use it for simulation with DNA in 
> complex. I am using amber 03 force field for my system . i have included 
> correctly the drg.itp file in generated topology file for DNA alone 
> (using pdb2gmx).
> i  managed  to run upto genbox successfully ,but when i tried to run 
> grompp it showed error
> "Atom type 'CH1' not found !"
> where i have to modify the things to work it properly .

Start by not mixing force fields.  There is no reason to believe that anything 
produced by PRODRG would be compatible with an AMBER force field.  Hence why 
PRODRG says it produces GROMOS-compatible topologies, with no mention of AMBER 
of any of the others.  The underlying derivation of the force fields and general 
theory (united-atom vs. all-atom being a major one) make these force fields 

To properly treat your system, it should be fairly straightforward to use 
antechamber or acpypi to develop your ligand parameters.



Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080


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