Effect of an impurity on 3-electron quantum dots in magnetic fields

The ground-state property of a 2-dimensional 3-electron quantum dot (QD) subjected to an external magnetic fieldB and affected by an impurity is studied. The impurity is located at thez-axis by a distanced from the plane of the dot. The evolution of the angular momentumLo and the spinSo of the ground state in accordance withB andd has been calculated, and the results are summarized and plotted in a (Lo,So) diagram. The spatial distribution of the electrons (the size and the geometric features) and the optical absorption have also been investigated. The (LoSo) diagram indicates thatLo andSo may jump whend and/orB vary. It was found that, due to the constraints arising from symmetry, each symmetric geometry is accessible only to a specific group of states having specificLo andSo.