[gmx-users] Old charmm force field

Justin Lemkul jalemkul at vt.edu
Wed Feb 5 00:10:52 CET 2014

On 2/4/14, 5:46 PM, Mark Abraham wrote:
> IIRC 19 had only protein and same as 27!

CHARMM19 did indeed have only protein parameters, but CHARMM27 isn't actually a 
protein force field, it's nucleic acids :)  CHARMM19 is united-atom, while all 
of the more recent versions of the force field (CHARMM22, CHARMM22+CMAP, and 
CHARMM36) are all-atom.  What people refer to as CHARMM27 includes CHARMM22 
protein parameters, so in this respect, CHARMM22 and CHARMM27 are equivalent 
with respect to proteins.

There are several versions of a script call charmm2gromacs.py floating around on 
the web.  These are designed to convert CHARMM RTF and PRM files into a suitable 
Gromacs-format force field directories.


> Mark
> On Feb 4, 2014 8:55 PM, "Sanku M" <msanku65 at yahoo.com> wrote:
>> Hi
>>    I need to reproduce a simulation result which had been performed using a
>> very old version of charmm forcefield (PARAMh19 forcefield). In order to
>> reproduce it correctly, I would like to use same forcefield that had been
>> used there.
>> I wonder whether there is any gromacs version of this old charmm
>> forcefield? If not, is there any any existing script which can convert the
>> charmm forcefield to gromacs format?
>> Thanks
>> Sanku
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Justin A. Lemkul, Ph.D.
Postdoctoral Fellow

Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 601
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201

jalemkul at outerbanks.umaryland.edu | (410) 706-7441


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