Electronic structures in a quantum dot with asymmetric confining potential

N-electron eigenstates in circular-, elliptic-, and triangular-shaped quantum dots (QDs) are calculated by numerically diagonalizing the N-particle Hamiltonian. In a circular QD, addition energy, or required energy to add one more electron to the QD, exhibits large values for N = 2 and 6 due to the complete shell filling, and shows a slightly large value for N = 4 which corresponds to a spin-polarized half-filling shell structure. In elliptic QDs, the degeneracy of the single-particle states is removed, resulting in transition of the ground state from the spin-polarized half-filling configuration to the spin singlet state in a QD containing four electrons. The states with 3, 6, and 9 electrons in a triangular QD are found to be slightly stable compared to a circular QD, which is interpreted in terms of a geometrical effect. (C) 1998 Elsevier Science B.V. All rights reserved.