On 6/30/13 12:11 PM, Hyunjin Kim wrote:
Hi,
When I convert FF parameters from OPLS (in Gromacs) to Charmm, I divide
bond and angle force constants, i.e., Kb and Ktheta, by 836.8 and 8.368.
However, parameters for tip3p water do not convert properly in this ways.
For example, Kb = 502416.0 kJ/mol/nm^2 for OW-HW in Gromacs and 450.0
kcal/mol/A^2 in Charmm.
502416.0/836.8 = 600.4 instead of 450.0.
I wonder what I did is incorrect.
CHARMM has its own special variation of TIP3P that corresponds to the values you
are trying to produce. In tip3.itp, it's the #ifdef CHARMM_TIP3P block. The
other parameters are for standard TIP3P.
-Justin
--
==================================================
Justin A. Lemkul, Ph.D.
Postdoctoral Associate
Department of Pharmaceutical Sciences
School of Pharmacy
Health Sciences Facility II, Room 601
University of Maryland, Baltimore
20 Penn St.
Baltimore, MD 21201
jalem...@outerbanks.umaryland.edu | (410) 706-7441
==================================================
--
gmx-users mailing list gmx-users@gromacs.org
http://lists.gromacs.org/mailman/listinfo/gmx-users
* Please search the archive at
http://www.gromacs.org/Support/Mailing_Lists/Search before posting!
* Please don't post (un)subscribe requests to the list. Use the
www interface or send it to gmx-users-requ...@gromacs.org.
* Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
