We construct an extended Hubbard model with open boundaries from a R-matrix based on the U q [Osp(2|2)] superalgebra. We study the reflection equation and find two classes of diagonal solutions. The corresponding one-dimensional open Hamiltonians are diagonalized by means of the Bethe ansatz approach.

We give a simple proof to derive the optimal flux which minimizes the ground state energy in one dimensional Hubbard model, provided the number of particles is even.

A symmetrized Density Matrix Renormalization Group procedure together with the correction vector approach is shown to be highly accurate for obtaining dynamic linear and third order polarizabilities of one-dimensional Hubbard and U−V models. The U−V model is seen to show characteristically different third harmonic generation response in the CDW and SDW phases. This can be rationalized from the ...

A class of quantum lattice models is considered, with Hamiltonians consisting of a classical (diagonal) part and a small oo-diagonal part (e.g. hopping terms). In some cases when the classical part has an innnite degeneracy of ground states, the quantum perturbation may stabilize some of them. The mechanism of this stabilization stems from eeective potential created by the quantum perturbation....

We formulate the Hubbard model for the simple cubic lattice in the representation of interacting dimers applying the exact solution of the dimer problem. By eliminating from the considerations unoccupied dimer energy levels in the large U limit (it is the only assumption) we analytically derive the Hubbard Hamiltonian for the dimer (analogous to the well-known t − J model), as well as, the Hubb...

For one dimensional SU(n) Hubbard model, a pair of Lax operators are derived, which give a set of fundamental equations for the quantum inverse scattering method under both periodic and open boundary conditions. This provides another proof of the integrability of the model under periodic boundary condition. PACS Numbers: 46.10.+z, 05.40.+j, 05.60.+w e-mail: [email protected] Integrable strong...