[gmx-users] Issues Using CHARMM22* Force Field with GROMACS 5.1

Justin Lemkul jalemkul at vt.edu
Tue Nov 3 23:12:36 CET 2015

On 11/3/15 3:34 PM, David Rosenman wrote:
> Hello,
> I am trying to use the CHARMM22* force field and TIP3SP water model with
> GROMACS 5.1.
> I tried using charmm22star.ff.tgz listed here
> http://www.gromacs.org/Downloads/User_contributions/Force_fields
> However, I get the error:
> Fatal error:
> Unknown bond_atomtype cn9

Atom types are now case sensitive.  You'll have this issue with cn8 also, I 
believe.  Just change them to CN9, CN8, etc.


> upon using grompp with any mdp.
> I'm guessing the problem is that the field is no longer compatible with
> GROMACS 5.1, since it was posted on the website in 2012. Indeed, I had no
> issue working with it using GROMACS 4.6.5 in the past.
> However, at the moment, I only have access to GROMACS 5.1, so does anyone
> know if an updated version of CHARMM22* exists? And if not, would it be
> difficult for me to personally fix the compatibility issue?
> Or, perhaps I'm doing something else wrong?
> Thanks for your assistance.
> Best regards,
> David J. Rosenman
> Postdoctoral Researcher
> University of Delaware


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


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