DYNAMIC PROPERTIES OF 2-DIMENSIONAL HUBBARD CLUSTERS

Numerical results for the density of states, N(omega), to remove or add electrons and the optical conductivity sigma-1 (omega) are presented for a two dimensional Hubbard model. As technique we used the Lanczos method on finite clusters of 4 x 4 and square-root 10 x square-root 10 sites. If the coupling constant takes values comparable to the bandwidth i.e., U/t approximately 8 - 10, many experimental features found in the high-Tc cuprate superconductors are qualitatively reproduced. In particular we have observed states filling the Mott gap upon doping and the presence of a mid-infrared band in the optical conductivity.