The resonating valence bond wave functions in quantum antiferromagnets
  Projected-BCS wave functions have been proposed as the paradigm for the understanding of disordered spin states (spin liquids). Here we investigate the properties of these wave functions showing how Luttinger liquids, dimerized states, and gapped spin liquids may be described by the same class of wave functions, which, therefore, represent an extremely flexible variational tool. A close connection between spin liquids and 
Alberto Parola, Sandro Sorella, Federico Becca, and Luca Capriotti