[gmx-users] freezegroups

[Berk Hess]

> > > Hi,
> > > Bert, you probably have constraints?
> > Atoms in 1-D freezing might still move because the have constraints.
>
>yes that was it. After switching off the constraints the 1D freezing
>works. thanks! I guess this applies to both lincs and shake? (I used 
>lincs).
>

Yes, when a partical is completely frozen its inverse mass (which is only
used in the constraint algorithms) is set to 1e-30, which means does not 
move
during constraining. When a particle is partially frozen, it is constrained
as normal.

> > In 3-D freezing this probably does not happen, since frozen particles
> > are only constrained to frozen particles.
> > It is not easy to implement combined 1-D freezing and constraining.
> >
>
>I can imagine. Maybe a word of warning in grompp or in the manual would
>save people from being caught in the same trap?

That's a good idea.

Berk.




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