Plumed and Constrained Atoms

Frank von Horsten xxx.f... at
Mon Mar 16 12:47:45 UTC 2015

Dear Marcella,

I downloaded the latest trunk version (15166) today and it solves the 

Thanks a lot for the quick reply and the fix!


On Sunday, 15 March 2015 07:17:01 UTC+1, Marcella Iannuzzi wrote:
> 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
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