how to get aimdirection to work for particles on a polyplane.
 

I have created a polyplane, an emitter than emits an equal number of particles to the number of vertices on the polyplane, and I've made the polyplane a goal for the particles so that they stick to the vertices. I will later animate the surface of the polyplane and need the particles (which hold instanced geometry) to aim in the right direction depending on the normals of the vertices. The particles will not move along the surface, but stay on the vertices.

Exactly what do I enter in as an expression to get this to work. I am not using goalU and goalV because I don't need it because I want the particles to be evenly spaced from each other (it was too much of a mess using a NURBS surface). Do I still use the pointOnSurface command? If so, how? I don't know how to set it up so that the aimdirection starts working.

Thanks.