[CP2K:3130] Re: Metadynamics Bug report in colvar: DISTANCE

Laino Teodoro teodor... at gmail.com
Thu Mar 3 06:03:26 CET 2011


Ata,

I'm sorry to say that PBC are implemented correctly and that NINT is the correct way to handle them - not just for CP2K, but for a series of other codes. Actually INT would seriously provide jumps (check its definition on the same link of my previous message)!!!

>From your previous mail, I have the suspect that your compiler is messing up the NINT and INT function definitions.

Your issue ( if there is one !! I thought a bit more during this night and honestly I am not sure that anything related to the lagrangian could be the source of your problem  ) is located somewhere else and deleting the NINT is only hiding the real problem. 

Be careful to what you say and to the message you give to other users (who may wrongly listen to your suggestions): in a full PBC calculation does NOT make any sense to use a DISTANCE colvar for metadynamics that does not comply  with PBC!

Regarding lagrangian and non-lagrangian the same comment as for the 200 cutoff : do what you like but do not give wrong messages around.

Regards,
Teo

---------------------------------------------
Teodoro Laino
Zurich Switzerland

Contact info:
Tel.:     http://www.jajah.com/Teo
E-mail: teo... at laino.eu
             teodor... at gmail.com
---------------------------------------------

On 3 Mar 2011, at 00:11, Ata Roudgar <rou... at yahoo.com> wrote:

> 
> 
> On Mar 2, 2:01 pm, Teodoro Laino <teodor... at gmail.com> wrote:
>> Dear Ata,
>> 
>> finally the situation is clear : the problem is not the CV itself, rather the extended lagrangian scheme, which does not take into account the PBC.
> 
> 
>> 
>> Thanks for pointing this out, we will fix this problem ASAP.
>> The correct fix is anyway not to comment the line containing NINT, rather taking care of PBC in the extended lagrangian scheme.
>> 
> 
> 
> As you saw from my input file the jump on CV is not even happen at the
> edges of the unitcell, it happens at the center of unitcell. That
> means that even PBC does not work correctly. A further research shows
> that the best would be to replace NINT to INT function without doing
> anything else.
> 
> 
>> Just for completeness: if you run a non-lagrangian MTD (which is what 90% of the people do nowadays) you will not see any jump and everything will run OK.
> 
> I thought 90% of the people do use lagrangian MTD since it provide a
> smooth transition.
> 
> Cheers,
> Ata
> 
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