Re: [ESPResSo] Specification of External Potential/Force

[Axel Arnold]

Am Dienstag 19 Februar 2008 19:23 schrieb Torsten Stuehn:
> You could do this by adding a wall-constraint to your simulation.
> The interaction of constraints (like a wall) with particles is like a
> non bonded interaction between to particles.
> Unfortunately there is currently no harmonic force/potential implemented
> for non bonded interactions. You could help yourself with a tabulated
> potential (file: 1st line: # <number of values> <minval> <maxval>
> following lines: <distance> | <force> | <energy>    ,ESPResSo will
> interpolate linearly between values):
>
>   inter 1 0 tab <filename>
>   constraint wall normal  0 0 1 dist 1 type 1
>
> Do the same for x and y direction.
> I never tested a set of rectangular wall constraints though, but it may
> work.
Hi all!

Unfortunately this will not work, because at the moment, constraint 
interactions are hard-coded to be of Lennard-Jones type. It would however be 
trivial to change the code to instead use the appropriate add_nonbonded_xxx 
routines.

Axel

-- 
Dr. Axel Arnold 
Fraunhofer Institute for Algorithms and Scientific Computing (SCAI)
Schloss Birlinghoven
53754 Sankt Augustin
Germany