Encapsulated spin function for periodic lattices

Abstract.

An approximate spin function for infinite periodic spin lattices is introduced. The “encapsulated spin function” is built from spin blocks variationally determined on open clusters. It gives a zeroth-order description of the short-range spin correlation while insuring a proper translational symmetry with an appropriate projection of the local spin function over the entire lattice. A recursion expression is derived that removes the normalization difficulty that arises in the projection. The one-dimensional Heisenberg regular Hamiltonian is tested in the present paper but the model allows for more complicated topologies of the interactions, including long-range exchange and three-spin exchange.