Spin-projected unrestricted Hartree-Fock ground states for harmonic quantum dots

We report the results for the ground state energies and wave functions obtained by projecting spatially unrestricted Hartree-Fock states to eigenstates of the total spin and the angular momentum for harmonic quantum dots with N <= 12 interacting electrons including a magnetic field. The ground states with the correct spatial and spin symmetries have lower energies than those obtained by the unrestricted method. The chemical potential as a function of a perpendicular magnetic field is obtained. Signature of an intrinsic spin blockade effect is found.