Re: Pulling only one half of a harmonic restraint

From: Jérôme Hénin (jerome.henin_at_ibpc.fr)
Date: Fri Sep 13 2019 - 04:19:50 CDT

Hi Miro,

Within the atom group block you can specify: "enableForces off".
Of course this changes the physics of what the harmonic restraint does: the
net force is halved (effectively halving the force constant), and its net
contribution to center-of-mass motion becomes nonzero.

Jerome

On Fri, 13 Sep 2019 at 10:06, Miro Astore <miro.astore_at_gmail.com> wrote:

> Hi all,
>
> I would like to pull on the atoms in group1 but not the ones in group 2.
> Help on how to do this would be appreciated. Example Colvar below
>
> colvarsTrajFrequency 500
> # Pulling
> colvar {
> name Pulled
> outputAppliedForce yes
> distance {
> group1 {
> atomsFile atoms.pdb
> atomsCol O
> atomsColValue 1.0
> }
> group2 {
> atomsFile atoms.pdb
> atomsCol O
> atomsColValue 2.0
> }
> }
> }
> harmonic {
> colvars Pulled
> centers 34
> targetCenters 4
> targetNumSteps 30000
> forceConstant 4.0
> }
>
> Best, Miro
>

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