Exact ground state properties are presented by combining the exact diagonalization of the Hamiltonian (including all hopping integrals and all two-site interactions) with ab initio optimization of the single-particle (Wannier) functions. Such a procedure is carried out for linear systems up to N=12 atoms. We study the system evolution as a function of lattice parameters. Electrons are essentially localized for the interatomic distance R > 2.2 Å. The statistical distribution evolves from the Fermi-liquid limit (at R 1 – 2 Å) to continuous momentum distribution for R > 2.2 Å. The single-particle correlation functions are also discussed.