[CP2K:87] Re: metadynamic

Teodoro Laino teodor... at gmail.com
Sun May 27 10:37:02 CEST 2007


If you ensure an enough large NT_HILLS this criterion is totally  
fulfilled (without
need to implement anything..).. how large? this depends on the nature
of your collective variable... (30 fs.. 40 fs.. 100 fs.. ??)...

NT_HILLS should be large enough to average all the fast degrees of  
freedom
of your system between one hill and the other.. so.. you can easily  
see that
even the condition you were mentioning is not SAFE. the time between
one hill and the other COULD be by far larger than the 3/2 criteria  
you were
mentioning since in that simulation time you may have not averaged  
anything..

Since it looks like you know very well metadynamics  than you know  
also that
the  choice of the parameter is fundamental in order to sample   
properly  the
free energy surface.
This means that there's no safe for procedure but a lot of experience  
to put
into your calculations and this unfortunately cannot be easily  
transformed into
a black box..

teo

On 27 May 2007, at 03:25, lml... at gmail.com wrote:

>
> Would someone be so kind to implant the Distance Criterion for the
> metadyanimcs (Ensing et. al, J Phys. Chem, B, 109, 6676)? At present,
> there is only minimu step, NT_HILLS (the number the interval of time
> step to spawn the hills), sometimes, there may be not very safe.
>
> As described on page 6683 of  Ensing et. al, Distance Criterion
> Method  requires that both (1)minimu step and (2)minimum displacement
> of collective variable (such as 3/2 Width of Hill)before adding a new
> hill. (3)And If the collective variable does not move the minimum
> displacement within a maxmium step, then it adds hills.
>
> Best Regards,
> Limin
>
>
>
> >




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