Orbital Picture of Ionization and Its Breakdown in Nanoarrays of Quantum Dots

We present exact numerical results indicating that ionization could be a useful tool to study electron correlations in artificial molecules and nanoarrays of metallic quantum dots. For nanorings consisting of Ag quantum dots of the type already fabricated, we demonstrate that the molecular orbital picture breaks down even for lowest energy ionization processes, in contrast to ordinary molecules. Our ionization results yield a transition point between localization and delocalization regimes in good agreement with various experimental data.

Figure 1

Dependence on the interdot spacing $d$ in Ag nanorings of (a) model parameters, (b) ionization potentials $I$ ($ϵ=-4.5\mathrm{e}\mathrm{V}$), and (c) spectroscopic factors $w$ for HOMO ionization. In (b) and (c), full (dashed) lines represent exact results for closed (open) shells; dotted lines are SCF results. (Number of QDs is written on the curves.)

Figure 2

Results for nanorings with $N=10$ Ag QDs, illustrating that a transition from a localization regime to a delocalization one occurs by varying $d$ in the range of present experimental interest.