ANDERSON LOCALIZATION FOR 2 INTERACTING ELECTRONS IN A DISORDERED CHAIN

We present an exact diagonalization study of the localization properti es and the corresponding dynamics for two electrons interacting via on -site Hubbard terms in a finite disordered chain, We obtain three kind s of two-electron states: (i) states almost unchanged by the interacti on with the two electrons well separated from each other, (ii) others with the localization length increased by the interaction, and (iii) s tates for which the interaction decreases the localization length. The physical origin of these states and their distribution in the band is examined from weak to strong interactions.