[gmx-users] In itp file from prodrg, what is C0 and C1 in bonds, angles and dihedrals section

Justin Lemkul jalemkul at vt.edu
Sat Oct 25 23:22:15 CEST 2014

Please keep the discussion on the mailing list.

On 10/25/14 5:11 PM, fatemeh ramezani wrote:
> I want to replace one atom parameter in itp file from prodrg result. I have
> epsilon and sigma of desired atom. How can I convert epsilon and sigma to C0 and
> C1?

You don't.  Sigma and epsilon are nonbonded parameters that are introduced in an 
[atomtypes] directive before any [moleculetype] is defined.  See Chapter 5 of 
the manual.  Note that Gromos force fields do not use sigma and epsilon; you 
have to convert them to C6 and C12 (which have no relation to these C* 
constants, which are only take their names from data structures used in the code).



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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