DENSITY-OF-STATES IN THE T'-HUBBARD MODEL - EXACT DIAGONALIZATION RESULTS

We calculated the density of states in a Hubbard model with nearest an d next nearest neighbour hopping. Using an exact diagonalisation techn ique, we examined this model in a wide area of parameters. The density of states was calculated for different fillings and for positive and negative interaction U. The additional hopping to the next nearest nei ghbour sites has different effects on the gap between the particle and hole spectrum compared to the pure Hubbard model.