Quantum generalized constant coupling model for geometrically frustrated   antiferromagnets
  A generalized constant coupling approximation for quantum geometrically frustrated antiferromagnets is presented. Starting from a frustrated unit, we introduce the interactions with the surrounding units in terms of an internal effective field which is fixed by a self consistency condition. Results for the static magnetic susceptibility and specific heat are compared with previous results in the framework of this same model for the classical limit. The range of applicability of the model is discussed. 
A. J. Garcia-Adeva and D. L. Huber