Preferred ground states of a quantum dot under a strong magnetic field

The ground-state energies of several interacting electrons confined in a parabolic dot in two dimensions are obtained by using hyperspherical coordinates and high-order perturbation theory. The effect of a perpendicular magnetic field is to change the ground state discontinuously in orbital angular momentum L. The preferred values of L for the ground state and the associated electronic structures are studied in detail. It is found that the effective interaction between two electrons moving in different cyclic orbits is a short-range attraction matched to a long-range repulsive tail. Because of this, electrons tend to fill adjacent cyclic orbits and form bunches in the ground states. The effects of an impurity ion are also considered.