Numerical studies of transport properties through artificial atoms and molecules

Transport properties are studied numerically through a quantum dot in which one-electron level spacings are comparable with the Coulomb interaction energy. Many-body ground state and excited states are obtained by the exact diagonalization method. An atomic-like shell structure of energy levels is reflected in peak positions of the Coulomb oscillation, whereas almost degenerate levels in a shell cause anomalous temperature dependence of some peak heights. When such artificial atoms are coupled like a molecule, the electronic correlation makes the Heitler-London wavefunction in which electrons are localized to be apart from each other. This correlation effect influences the peak heights of the Coulomb oscillation through the artificial molecule. (C) 1998 Elsevier Science Ltd. All rights reserved.