Simulation of correlated electron tunneling and a Coulomb blockade in a quantum-dot diode

We investigate the effects of electron exchange and Coulomb correlations on resonant tunneling in a quantum-dot diode by numerically solving the two-electron time-dependent Schrödinger equation. Electron-electron interaction effects for spin-parallel and spin-antiparallel electrons give rise to specific peaks in the transmission probability. These features resemble the observed fine structure in the I-V curves. The results of two-electron simulations are used to assess the validity of theoretical approaches such as the Hartree-Fock approximation and the local-spin-density approximation (LSDA), with and without the self-interaction correction, in the density-functional theory. Unlike the LSDA, the time-dependent Hartree-Fock approximation and the self-interaction-corrected LSDA work well for a quantum-confined electron pair. The implications of these simulation results on the many-electron transport in ultrasmall devices is also discussed.