THE GROUND-STATE PHASE-DIAGRAM OF THE KONDO-LATTICE MODEL

The groundstate phase diagram of the one dimensional Kondo lattice mod el is obtained by combining exact results at various limiting cases an d numerical exact diagonalization study. In particular it is shown tha t the groundstate at half filling is a spin liquid state for any excha nge coupling. Crossover behavior in the Kondo spin liquid state among its limiting cases (the hybridization gap state, the local singlet and the collective singlet) is discussed in connection with the Kondo ins ulators.