Anisotropic tight-binding model for localization.

The anisotropic tight-binding model, which is defined by a disordered tight-binding Hamiltonian with a transfer-energy-matrix element in the {ital z} direction, {ital t}, different than the one in the {ital x}-{ital y} plane is studied using finite-size scaling methods. The dependence of the mobility edge on the strength of anisotropy {ital t} (0{le}{ital t}{le}1) is obtained for the center of the band, {ital E}=0. Even for very low-{ital t} values an appreciable amount of disorder is needed to localize the {ital E}=0 state. These results are found to be in satisfactory agreement with the predictions of the potential-well analogy, coupled with the coherent-potential approximation.