QMC Study of Quantum Dots with Strong Interactions

We study the interplay of Coulomb repulsion and shell effects for electrons confined in a circular parabolic quantum dot. We use variational and diffusion Monte Carlo methods to calculate the ground state, excitation energies, and addition energy. We focus on the dependence of these quantities on both the total electron number, N up to 20, and the electron gas parameter (which measures interaction strength), $r_s$ up to about 10. For strong interaction our results show violations of Hund's second rule, which is expected. Strong interaction drives an electron gas toward Wigner crystallization; it is thought that nanoscale confinement may affect significantly this process, leading perhaps to ``incipient" crystallization. With regard to the latter, we present results for the pair correlation function and discuss implications.\\ This work was supported by the NSF (DMR-0103003 and DMR- 0205328).