Effects of electron-electron interactions on the nature of the eigenstates in amorphous materials

A Hubbard model with random site energies is used to investigate the electron localization effects associated with both disorder and electron-electron interactions on a Cayley tree. Extensive results have been reported on the ground states properties of the system. In particular, two regimes have been found: if the electron-electron interaction parameter U is greater than the disorder parameter W, it appears to be significant in localizing electronic states otherwise it may be viewed as weakly perturbating the effects of the disorder. (author). 30 refs, 3 figs