Charging energy and spin polarization in artificial atoms and molecules

We investigate the electronic properties of single and coupled quantum dot systems by a self-consistent solution of Schrödinger and Poisson equations within the density functional theory. The single and coupled quantum dots show remarkable similarities to atoms and molecules. We observe that in the case of single quantum dots with cylindrical symmetry, the electrons in the dot form shells like in atoms. This sheel structure is slightly distorted due to the electron-electron interaction, as the number of electrons, N, increases. In the case of coupled quantum dots, we observe that the dots can be driven from a state wherein the individual dots are separate, akin to two isolated atoms, to one in which the dots couple forming an “artificial molecule.” By using the local spin density approximation, we observe spin polarization in the double dot for specific values of N.