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Using a Lanczos technique we study the frustrated spin- (1/2 Heisenberg model on square lattices of 16 and 20 sites. Frustration is introduced by an interaction along the diagonals of the plaquettes with coupling J₂0. For large J₂ we found that the ground state breaks (spontaneously) the lattice rotational symmetry. For intermediate values of J₂, the squares of order parameters associated with spin-Peierls and ``twisted'' states have a peak while a similar quantity for a chiral state shows no interesting structure.
Dagotto et al. (Mon,) studied this question.