[lammps-users] Confining particles to a cylindrical surface

I would like to confine a population of particles to the surface of a cylinder. (1) One way I can think to do this is to apply a harmonic restoring force to these particles holding them at a fixed distance from an axis. (2) Alternatively I could build a cylindrical "sticky" (a modified LJ 12-6 ?) wall that all particles are attracted to. (3) I suppose I could also build a cylinder out of a population of sticky fixed particles, but I would be concerned that the roughness of that wall might affect how the non-fixed particles interact with the wall.

(3) seems possible within the command library. (1) and (2) seem outside the available command library and may require modifying the source code. Comments?

None of your suggestions will confine atoms
exactly to a cynlinder. To do that I think you'd
have to write a new fix. If you just want them
near the surface, then (1) seems OK. But I don't
think any of the spring fixes does exactly what you