Exactly solvable Kondo-lattice model.

In this work, we solve exactly a Kondo lattice model in the thermodynamic limit. The system consists of an electronic conduction band described by unconstrained hopping matrix elements between the lattice sites. The conducting electrons interact with a localized impurity spin at each lattice cell. We have found the exact thermody-namics, the ground state energies of the system. At T = 0, we explicitly demonstrate that the system exhibits a metal-insulator phase transition at half-filling. In the limit of strong coupling between the impurity spin and the conduction electrons, J = +∞, we have solved the system on a lattice of any size L. The ground states are the RVB-type Jastrow product wavefunctions. Various correlation functions can be computed for the impurity spins, and for the singlets formed by electrons and impurities.