Abstract: Ground-state energy of a planar quantum dot with two electrons is calculated with perturbation theory, numerically exact diagonalization and variational theory. Compared with earlier unrestricted Hartree-Fock studies, it is shown that a three-parameter variational wave function is an excellent representation of true ground state. It provides references for the understanding of planar quantum dots with more electrons.

Key words: quantum dot, parabolic confinement potential, ground-state energy