Stabilization of ground-state minimal spin in disordered quantum dots

We investigate the ground-state spin and energy of disordered quantum dots using spin-density-functional theory. With increasing interaction strength, the probability of non-minimal spin increases, but never exceeds 50%. Within a two-orbital model, we show that the off-diagonal Coulomb matrix elements help stabilize a ground state of minimal spin by creating a low-energy hybridization of the various minimal-spin basis states.