An exact method to solve the diluted extended Hubbard model

Chumín Wang, Oracio Navarro, Raúl Oviedo‐Roa

Y. Ohta, Kenji Tsutsui, Wataru Koshibae +1 more

M. Bąk, R. Micnas

We examine extended bound states in a dilute limit of the extended Hubbard model on the two-dimensional square lattice.By solving exactly the two-body problem we have determined the binding energies, mobilities, and dispersion curves across the Brillouin zone for bound states of various symmetries.It turns out that the d-wave pairing is strongly favored by the nnn hopping and the intersite local pairs can have small effective masses, even in the case of strong binding.We have also found a possibility of extended S-d2-2 mixing of the bound states.

Pavol Farkašovský

Ferdinando Mancini, Francesco Paolo Mancini, Adele Naddeo

We study the phase diagram at finite temperature of a system of Fermi particles on the sites of the Bethe lattice with coordination number z and interacting through onsite U and nearest-neighbor V interactions. This is a physical realization of the extended Hubbard model in the atomic limit. By using the equations of motion method, we exactly solve the model. For an attractive intersite potential, we find, at half filling, a phase transition towards a broken particle-hole symmetry state. The critical temperature, as a function of the relevant parameters, has a re-entrant behavior as already observed in the equivalent spin-1 Ising model on the Bethe lattice.

Heng Fan

We propose two-leg fermion-ladder models for the SU (2|2) and SU (4) cases. The former is exactly the extended Hubbard model proposed by Essler, Korepin and Schoutens. The latter is a new model also with -pairing symmetry which is important for superconductivity. This new extension of the Hubbard model can be solved exactly.