Hubbard model with infinite-range hopping

J.-B. Bru, T. C. Dorlas

M W Long

For the Hubbard model with infinite-range hopping, a sensible competition between hopping and Hubbard repulsion can only be found when U/t scales with the volume of the system. Only two electrons carry all the kinetic energy and so the variations in Hubbard repulsion are bounded by only 2U for an eigenstate. To be comparable with the kinetic energy this must be extensive. For this case the author derives some exact eigenstates for the model. The lowest energy solution is paramagnetic although the spin degeneracy energy scale is very small. The behaviour of this system appears to be very different to that for the shorter-range hopping systems and so little can be deduced about more physical models.

Florian Gebhard

Flavio S. Nogueira, E. V. Anda

A toy model of strongly correlated fermions is studied using Green function and functional integration methods. The model exhibits a metal-insulator transition as the interaction is varied. In the case of unrestricted hopping is established the equivalence of the model with the Hubbard model with infinite range hopping. The generalization to the case with $N$ components is made.

Cary Mcilwaine Maguire

Shuichi Murakami

A new integrable variant of the one-dimensional Hubbard model with variable-range correlated hopping is studied. The Hamiltonian is constructed by applying the quantum inverse scattering method on the infinite interval at zero density to the one-parameter deformation of the L -matrix of the Hubbard model. By construction, this model has symmetry in the infinite chain limit. Multiparticle eigenstates of the model are investigated by using this method.