We review our recent results concerning the electronic properties of a nanoscopic system with inclusion oflong‐rangeCoulomb interactions that are obtained by combiningexact diagonalizationin the Fock space with anab initiomethod (EDABI). The system evolution is discussed as a function of lattice parameterR. A transformation from a nanometal to localized spin system is observed. With the help of afinite‐size scalingwe determine the discontinuity of the momentum distribution at the Fermi points. Our results implyFermi‐liquid‐like behaviorforR≲ 3a0(a0is the Bohr radius). The quasiparticle mass is almost divergent at the localization threshold, where the particle distribution of the Fermi‐Dirac type gets smeared out. The charge‐gap evolution is compared with that of the Slater gap. Also, the single‐particle spectral function and the corresponding density of states are presented. The analysis is performed using 1s‐like Gaussian‐type STO‐3G basis. © 2003 American Institute of Physics