tclForces - addforce to group of atoms

From: Jan Saam (
Date: Fri Jan 07 2005 - 17:01:13 CST

Hi all,

does anyone know what exactly happens when I apply a force to a group of
atoms using the tcl intrface?

Assume something like this:
I speccify a group of 5 atoms using "addgroup" ten I apply a force of
1000 kcal/mol/A to it.

Will each atom be pulled with 1000 kcal/mol/A or will the force be
distributed among the atoms so that each one feels only 200 kcal/mol/A.
Or is the force even scaled with the mass?


tclForcesScript {

set group [addgroup 1 2 3 7 10]

proc calcforces {} {

     global group

     ... # do stuff

     addforce $group 1000

Thanks for help,


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