Electron correlations in two-dimensional small quantum dots

TL;DR

This paper investigates how electron correlations affect the ground state properties of small two-dimensional quantum dots, revealing significant changes in spin structure and the destruction of certain ordered states.

Contribution

It introduces a combined Hartree-Fock and second-order perturbation approach to analyze electron correlations in quantum dots, highlighting effects overlooked by mean-field methods.

Findings

Correlations qualitatively alter the ground state's spin structure.

Correlation effects can destroy Hund's rule in quantum dots.

Static spin-density waves are suppressed by electron correlations.

Abstract

We consider circular and elliptic quantum dots with parabolic external confinement, containing 0 - 22 electrons and with values of r_s in the range 0 < r_s < 3. We perform restricted and unrestricted Hartree-Fock calculations, and further take into account electron correlations using second-order perturbation theory. We demonstrate that in many cases correlations qualitatively change the spin structure of the ground state from that obtained under Hartree-Fock and spin-density-functional calculations. In some cases the correlation effects destroy Hund's rule. We also demonstrate that the correlations destroy static spin-density waves observed in Hartree-Fock and spin-density-functional calculations.