  We propose that the valence bonds forming the ground state of the 2D-AF
Heisenberg model on a square lattice may rotate under the effect of the
antiferromagnetic background. To test this idea we apply a real space
renormalization group approach to construct a rotating-valence-bond ground
state anstaz. Our results are analytic and valid for any value of the spin S of
the AF-magnet, which allow us to perfom semiclassical expansions of the energy
and the staggered magnetization.
