Plumed and Constrained Atoms

[Marcella Iannuzzi]

Dear Frank,

Metadynamics + fix atom constraints should work without restriction using 
the cp2k metadynamics implementation.
Now, i.e., using the trunk version of cp2k, fix constraints should also 
work with plumed metadynamics.

For other type of constraints, i.e. defined through collective variables, 
the metadynamics forces are not projected out,
hence there would be inconsistencies if one atom is simultaneously involved 
in a metadynamic variable and in a constraint.

regards
Marcella


On Friday, March 13, 2015 at 11:57:06 AM UTC+1, Frank von Horsten wrote:
>
> Dear All,
>
> I have a question regarding constrained atoms in combination with 
> metadynamics using plumed.
>
> I have a small system in which I want to constrain some atoms. This works 
> as expected when I run the calculation without plumed.
> However, with plumed turned on, one of the constrained atoms starts 
> moving. The only difference is that this atom is part of the collective 
> variable CV, which is defined as the distance between that atom and another 
> unconstrained one.
> A look on the forces shows that these are not zero for the constrained 
> atom, which is part of the CV when plumed is on.
>
> So the question is, whether the constraints are not applied to atoms, 
> which are part of the CV? Or in other words: is this a bug or a feature?
>
> I tested this for CP2K 2.5.1 + plumed 1.3 and one of the latest SVN 
> versions + plumed 2.1.1. Also it happens for FIST and QUICKSTEP.
>
> Thanks and best wishes
> Frank
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20150314/47fcc12c/attachment.htm>