Nonuniversal transmission phase lapses through a quantum dot: an exact diagonalization of the many-body transport problem.

Systematic trends of nonuniversal behavior of electron-transmission phases through a quantum dot, with no phase lapse for the transition N = 1-->N = 2 and a lapse of pi for the N = 2-->N = 3 transition, are predicted, in agreement with experiments, from many-body transport calculations involving exact diagonalization of the dot Hamiltonian. The results favor shape anisotropy of the dot and strong e-e repulsion with consequent electron localization, showing dependence on spin configurations and the participation of excited doorway transmission channels.