APPLICATION OF THE GLOBAL SO(4) SYMMETRY IN THE DIAGONALIZATION OF TRANSLATIONALLY-INVARIANT CORRELATED ELECTRON MODELS

We present a method for the simultaneous implementation of the spin sy mmetry, the pseudospin symmetry and the translational invariance in mo dels for correlated electron systems on finite-size clusters. The appl ication of this method leads to a significative reduction of the size of the Hamiltonian matrix blocks, thus considerably simplifying the di agonalization procedure. We illustrate the method solving exactly the Hubbard model on a 8-site chain in the Hilbert subspaces labelled by t he eigenvalues of the spin, the pseudospin and the momentum operators. Some relevant thermodynamical quantities, such as the specific heat a nd the static magnetic susceptibility, are then evaluated and a brief discussion on the tendency of the model to exhibit ferromagnetism is a lso presented.