Akademisk avhandling för avläggande avc filosofie licentiatexamen vid Stockholms universitet: Performance of Many-Body Perturbation Theory calculations on 2D Quantum Dots

by Erik Waltersson (Fysikum, Stockholms universitet)

Monday 4 Jun 2007, 14:00 → 17:00 Europe/Stockholm

FA31

Many-Body Perturbation Theory is put to test as the future method for reliable calculations on few electron quantum dots. As starting points for the perturbation theory a variable exchange Local Density Approximation method and a variable exchange Hartree-Fock method are tested. The second-order results are compared with Configuration Interaction calculations and experiments. The model potential used is a two dimensional harmonic oscillator and the possibility to include effects of an external magnetic field applied perpendicular to the dot plane is included. Material parameters for GaAs are used. With confining potential strengths greater than or equal to 5 meV second order correlation is shown to include most physically interesting effects of the first two shells (N less than or equal to 6). For weaker potential strenghts and/or larger particle numbers spin contamination becomes an increasing problem with the Hartree-Fock starting point. Here a method that includes correlation beyond second order is necessary.