Mott Transition of the Half-filled Hubbard Model in a Two-dimensional Frustrated Lattice

Using coherent potential approximation we study zero-temperature Mott transition of the half-filled Hubbard model in a two-dimensional square lattice with geometrical frustration. It turns out that the geometrical frustration reduces the gap between the Hubbard bands. As a result the metallic phase is stabilized up to a fairly large value of the on-site Coulomb interaction. We found that the critical value UC for the Mott transition is enhanced by the geometrical frustration. Our results are in good agreement with the ones obtained by the single-site dynamical mean-field theory. Mott-insulator; Hubbard model; geometrical frustration; coherent potential approx- imation.