[gmx-users] charmm36 lipid forcefield error

[Justin Lemkul]

On 6/1/17 4:43 PM, Archana Sonawani-Jagtap wrote:
> Hi,
> 
> I want to perform GPCR simulation in POPC bilayer using Charmm36
> forcefield. I have generated the bilayer using CHARMM-GUI. I am following
> GPCR tutorial by Justin (modified to GPCR by Anirban).
> 

CHARMM-GUI gives you the required force field files.  Use those and don't mess 
with them.

> I want to remove periodicity of the generated bilayer using following
> command:
> 
> grompp -f EM.mdp -c popc288.gro -p topol_popc.top -o EM.tpr
> but I am getting below error:
> 
> Program gmx grompp, VERSION 5.1
> 
> Source code file:
> /usr/local/gromacs-5.1/src/gromacs/gmxpreprocess/gmxcpp.c, line: 312
> 
> Fatal error:
> 
> Topology include file "charmm36_lipid.ff/forcefield.itp" not found
> 
> I have downloaded Charmm36 FF from gromacs user's section and placed it in
> 

The force field files on gromacs.org are not authoritative CHARMM36 files and in 
fact contain a mixture of force field parameters (C36 for lipids, but C22+CMAP 
for protein, if I recall).  If you want correct C36 parameters, get them from 
our website:

http://mackerell.umaryland.edu/charmm_ff.shtml#gromacs

But again, CHARMM-GUI gave you everything you need, from the parent force field 
files all the way through the topology of the system, so you shouldn't have to 
touch any of this.

-Justin

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

Justin A. Lemkul, Ph.D.
Ruth L. Kirschstein NRSA Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 629
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalemkul at outerbanks.umaryland.edu | (410) 706-7441
http://mackerell.umaryland.edu/~jalemkul

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