[CP2K-user] [CP2K:21429] Constrain on collective variable

[bijaya pathak]

Dear MuS, 
Thank you for your suggestion.
I have defined my CV as you have suggested.  The issue is about not being 
able to restrain the  CV  at a particular value. As I have already stated, 
I need my CV within a certain value. Even with restrain as large as 1000 
kcalmol, the restrain condition does not hold. I am worried that I might be 
making some mistake in applying the restrain on CV. So could you please 
suggest anything about that ? 
Thanks and Regards 
Bijaya  

On Monday, April 28, 2025 at 12:48:59 PM UTC+5:30 Muhammad Saleh wrote:

> Hi, first of all 1000 kcalmol seems to high. For your error, it means you 
> need to specify which atom or molecule that your constrainst will be 
> applied, something like this 
>
>    &COLVAR
>      &DISTANCE
>        ATOMS 599 1008 # Atoms indexes where your constraint applied
>      &END DISTANCE
>     &END COLVAR
>
> Best
> MuS
>
>
> On Mon, Apr 28, 2025 at 6:29 AM bijaya pathak <bijayap... at gmail.com> 
> wrote:
>
>> Dear all, 
>> I'm running a meta dynamics simulation on cp2k, my collective variable is 
>> distance(covalent bond  length). Previously , I've applied restrain on CV 
>> but those were intermolecular. In the present case my input file looks like 
>> follows: 
>>
>> &CONSTRAINT
>>      &COLLECTIVE
>>        COLVAR  1
>>        TARGET [angstrom] 1.8
>>        &RESTRAINT
>>          K [kcalmol] 1000
>>        &END RESTRAINT
>>     &END COLLECTIVE
>> But it gives an *error*: 
>> "Constraint section error: you have to specify at least one of the 
>> following keywords: MOLECULE, MOLNAME or INTERMOLECULAR"
>>
>> *MOLECULE {Integer}* 
>> *Specifies the index of the molecule kind (in input file order)on which 
>> the constraint will be applied. MOLECULE and MOLNAME keyword exclude 
>> themself mutually.* 
>> This keyword cannot be repeated and it expects precisely one integer.
>> *MOLNAME {Word}* 
>> *Specifies the name of the molecule on which the constraint will be 
>> applied.* 
>> This keyword cannot be repeated and it expects precisely one word. 
>>
>> I do not understand what is meant my molecule kind in the input file . 
>> Can anyone help me with the issue ? I have tried various values for the 
>> keyword as per my understanding , but it gives error stating* index does 
>> not match.*
>> Any suggestions will be appreciated.
>> Thanking you 
>> Bijaya   
>>
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>>
>

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