Hund's rule, spin blockade, and the Aufbau principle in strongly confined semiconductor quantum dots

The ground-state configuration of a system of N electrons or holes (N = 1 ... 8) in strongly confined InAs, InP, and Si quantum dots (diameter similar to 30 Angstrom) is calculated using pseudopotential single-particle energies and wave functions as input to the many-body expansion of the total energy. The validity of generally accepted rules of level occupation (Hund's rule, Aufbau principle, and single spin-flip rule) is examined. We find that while Hund's rule is generally obeyed, deviations from the Aufbau principle are common when single-particle energy levels are separated by a few meV. We also find a few instances where the single spin-flip rule is violated, leading to spin blockade in linear conductance.