Hartree–Fock studies of quantum dots and the 0.7 anomaly

Abstract

We apply unrestricted Hartree–Fock to modelling two systems: (1) We calculate the spin structure and addition spectra of small symmetric quantum dots (often called 2D “artificial atoms”), improving the accuracy considerably by including, for the first time, second-order correlation corrections. We compare the results to experiment and to previous numerical works, and find that our spin structure in some cases disagrees with that calculated within mean-field theories, such as Hartree–Fock without correlation corrections, or density-functional theory [C. Sloggett, O.P. Sushkov, Phys. Rev. B 71 (2005) 235326]. (2) We model the well-known 0.7 anomaly in the conductance of a quantum point contact. We calculate the conductance using direct calculation of scattering phases on a ring, within Hartree–Fock. We observe strong localisation of the Fermi electrons on the barrier, and suggest a mechanism for the observed temperature-dependent conductance anomaly.