[gmx-users] Maximum Force constant for Position Restraints

Alex nedomacho at gmail.com
Tue Apr 21 21:13:55 CEST 2015

I think this can be estimated from a general physical argument. The
absolute max in my opinion should come from
4*pi*tau = sqrt(m/k), where m is the mass of the lightest restrained
particle in the system, k is the constant you seek, and tau is the
The coefficient is four because of the Nyquist theorem. I believe GMX tests
for high vibrational frequencies according to 20*pi*tau on the left (ten
times the period).

Hope this helps.


On Tue, Apr 21, 2015 at 1:02 PM, Marcelo Depólo <marcelodepolo at gmail.com>

> Hi guys!
> Is there a maximum value of Force Constant for Position restraints? Reading
> the Manual I could only find the default and the equation to describe it.
> Best,
> --
> Marcelo Depólo Polêto
> Group of Structural Bioinformatics - Center of Biotechnology
> Student of MSc Cell and Molecular Biology - UFRGS (Brazil)
> B.Sc. Biochemistry - University of Viçosa (Brazil)
> --
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