When all 3 dimensions of electron device drop to a nanometer size, a 0-D device or a quantum dot appears. In this case the conductance shows oscillations with varying gate voltage. In this paper the results of numerical simulations, which clearly show the above behavior, are presented. The dot conductance is calculated with the help of Landauer formula after the Green's function corresponding to device Hamiltonian is evaluated. Coulomb interactions are included as the Hartree potential associated with the charge of all particles inside a dot. This forces us to use self-energies which describes interactions between device and leads not only to propagating states but also to non-propagating, localized states below the band.

PACS numbers: 73.23.--b, 73.23.Hk