MOTT-HUBBARD METAL-INSULATOR-TRANSITION IN NONBIPARTITE LATTICES

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 U5.27t where a charge gap (0.085t) opens up. We also discuss the effect of fluctuations. © 1990 The American Physical Society.