Approaching periodic systems by a self-consistent embedding of a finite cluster

When using a Hamiltonian model, of Hubbard or Heisenberg type, one may approach the properties of a periodic lattice by embedding a finite cluster into a periodic localized function and by self-consistently dressing the configuration interaction matrix of the cluster under the effect of the charge or spin fluctuations of the neighbor bonds. The efficiency of the method is illustrated on the 1-D problem, for both Heisenberg and Hubbard Hamiltonians.