An efficient implementation of high-order coupled-cluster techniques   applied to quantum magnets
  We illustrate how the systematic inclusion of multi-spin correlations of the quantum spin-lattice systems can be efficiently implemented within the framework of the coupled-cluster method by examining the ground-state properties of both the square-lattice and the frustrated triangular-lattice quantum antiferromagnets. Various physical quantities including the ground-state energy, the anisotropy susceptibility, and the sublattice magnetisation are calculated and compared with those obtained from such other methods as series expansions and quantum Monte Carlo simulations. 
Chen Zeng (Syracuse Univ.), D.J.J. Farnell (UMIST), and R.F. Bishop   (UMIST)