[gmx-users] how to use charmm ff in gmx and carbohydrate forcefield

Tom dnaafm at gmail.com
Thu Mar 1 00:11:48 CET 2012

Dear Gromacs User and developers:

Please help with 2 questions:
1) Does the converted charmm forcefield (charmm36 or 27) in gromacs
include forcefield parameters for carbohydrate (sugar)?  I looked
through *itp and can not find them in converted charmm36 and 27 in

2) How to convert charmm forcefield parameters and use in gromacs?
To save time to look through gromacs source code, any expert can give
some guidances?

My question is beside the difference in the unit, like kcal, A
(charmm) vs.  kj, nm (gromacs),
do i need to care about any conversion of the potential format?

For example: i have a set of nonbonded and bonded parameters with the
original charmm
formate and want to use in gromacs, do i need to convert anything,
because of the format difference in the potential formula, such as
potential of vdw, bond, angle, dihedral angle, and improper dihedral
angle before i add them to *itp and *rtp file?

Thanks a lot for the information!


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