Re: [ESPResSo] Changing nonbonded tabulated interaction potentials in mid-run

[Axel Arnold]

On Monday 23 August 2010 09:39:09 Steven R. Kirk wrote:
> Hello!
>
> I'm using tabulated potentials for calculating interactions between
> particles of a single species. I want to alter this potential mid-run,
> and I also want change the number of points where the new potential is
> tabulated (currently I get the error message:
>
> number of data points does not match the existing table
>
> )
>
> So can I do the following:
>
> inter 0 0 tabulated tab_pot1.dat
>
> Then later in the script do:
>
> inter 0 0 tabulated tab_pot2.dat
>
> ?
> Do I need to remove the first interaction before specifying the second?
> Are there any alternative means to achieve the same goal (if so, would
> be very grateful for details).

Hi!

I am not using tabulated potentials myself, but a quick scan of this code 
shows that there is currently no way to change the number of points. The 
reason is, that there is one table, in which all the tabulated values are 
allocated, and if you would want to increase the number of points in one of 
the stored potentials, then all the potentials stored afterwards would need to 
be shifted, which simply isn't implemented and actually not so easy.

For your suggestion to delete the interaction: there is no way to delete an 
interaction. There is a table of interaction parameters for pairs of particles 
of certain types. Switching off a particular interaction simply means to set 
its cutoff to 0, so that it is not used for this specific pair of types. But 
there is no way to change the number of points in a tabulated interaction back 
to 0.

Axel

-- 
JP Dr. Axel Arnold Tel: +49 711 685 67609
ICP, Universität Stuttgart      Email: address@hidden
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70569 Stuttgart, Germany