We have applied our novel numerical scheme combining Lanczos diagonalization in the Fock space with an ab initio renormalization of the single-particle (Wannier) functions, to study the ground state properties of the  Extended Hubbard Model. Through the finite-size scaling we determine the discontinuity of the momentum distribution Fermi surface. Our results imply Fermi-liquid behavior for lattice parameter a \lesssim 3a₀ (a₀ is the Bohr radius) and zero-temperature transition to the localized spin system for larger a. Possible further applications of the method are listed at the end.

PACS numbers: 71.15.Dx, 71.30.+h, 71.10.Fd