Mott-Hubbard metal-insulator transition in nonbipartite lattices

Abstract

We reinterpret the Hubbard model in terms of doubly occupied sites and empty sites with an attractive interaction U whose pairing leads to the Mott-Hubbard transition. We develop a mean-field theory for this pairing which in a triangular lattice at T=0 leads to a first-order transition from a spiral, incommensurate metal to a commensurate insulator at U≃5.27t where a charge gap (≃0.085t) opens up. We also discuss the effect of fluctuations.