The Hall constant of correlated electrons: Cluster calculation for Hubbard model

We calculate the Hall constant R(H)(omega, T) for the high T(c) materials La(2-x)Sr(x)CuO(4) and YBa(2)Cu(3)O(7-x) using the 2D Hubbard model, on a cluster of dimension (2 x 3). Close to half filling, at low temperatures and high frequency, we find that R(H)(omega) is electronlike in the weak correlation regime and in the strong correlation regime it is holelike with roughly 1/T + const form. At high frequencies, for La(2-x)Sr(x)CuO(4) we obtain a change in the sign of R(H)(omega) at x similar to 0.3, which is in good agreement with the experimental data.