  We use the inverse participation ratio based on the Husimi function to
perform a phase space analysis of the Anderson model in one, two, and three
dimensions. Important features of the quantum states remain observable in phase
space in the large system size limit, while they would be lost in a real or
momentum space description. From perturbative approaches in the limits of weak
and strong disorder, we find that the appearance of a
delocalization-localization transition is connected to the coupling, by a weak
potential, of momentum eigenstates which are far apart in momentum space. This
is consistent with recent results obtained for the Aubry-Andre model and
provides a novel view on the metal-insulator transition.
