Adding the reference point for rigid bodies #5
Description
@gmadaria writes: How is the reference point of a rigid body expressed? In my opinion, it should appear in the list of atomic coordinates, with the name used in its definition. The reference point is important, since it could be the centroid of the rigid group, its center of mass, or any other point chosen by the user for convenience. The results should be identical regarding the position of the rigid body (which is not entirely true, because the rigid-body equations are linearized for refinements), but the parameters defining that position would be different.