[gmx-users] Turn off the diheral energy

Tsjerk Wassenaar tsjerkw at gmail.com
Wed Jan 30 08:57:28 CET 2008

Hi Myunggi Yi,

> Mixing force fields is an intrinsically bad idea. See
> http://wiki.gromacs.org/index.php/Parameterization

I second that...

> > Is it possible to turn off dihedral energy (proper and improper) for a
> > certain molecule?
> > If yes, then how can I do this?
> Comment out these parts of your topology file.

You can do this easily by enclosing the dihedral section with an
#ifdef ... #endif block, and use a control #define statement upstream
of it:


[ dihedrals ]

This even allows you to control it through the .mdp file, including the line


Hope it helps,


Tsjerk A. Wassenaar, Ph.D.
Junior UD (post-doc)
Biomolecular NMR, Bijvoet Center
Utrecht University
Padualaan 8
3584 CH Utrecht
The Netherlands
P: +31-30-2539931
F: +31-30-2537623

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