Exact result on the Mott transition in a two-dimensional model of strongly correlated electrons

We study the properties of a quarter-filled system of electrons on a square lattice interacting through a local repulsion U and a nearest-neighbor repulsion V in the limit V=+∞. We identify the ground state for U large enough and show that domain walls appear below a critical value ${\mathit{U}}_{\mathit{c}}$=4t/π. We argue that this corresponds to a metal-insulator transition due to Mott localization.