energy minimization


I'v put a set of atoms on the surface of a sphere sth like fulleren but
not exactly a fullerene. I want to minimize the energy of this setup to find
the stable structure of this sphere. i need to do this energy minimization
constrained to a surface sphere to avoid deformation of the shape.
the force field used is lj/sdk in cg/cmm package. and the bond and angle
is harmonic.
do you think i can use some kind of radial force to make atoms stable on
the sphere?

it might be possible to do this with some smart use of atom style variables.
- you define atom variables that contains the (normalized) vector
components of each atom position to the center of the sphere
(particularly easy, if the center was a [0.0 0.0 0.0])
- then you compute the projected force of each atom on this vector
- and use fix setforce to apply the updated force

it might be easier, though, to just program this in C++ as a custom fix.