Stabilita Fermiho kapaliny vůči dynamickým fluktuacím v silně korelovaných elektronových systémech

• Main Author: Augustinský, Pavel
• Other Authors: Janiš, Václav
• Format: Doctoral Thesis
• Language: English
• Published: 2011
• Online Access: http://www.nusl.cz/ntk/nusl-312134

In this thesis, we study quantum impurity models by means of the diagrammatic perturbation theory. First, parquet equations are simplified in the strong coupling regime and low temperatures and an analytically controllable approximation results. We apply it to both the single impurity Anderson model and the Hubbard model in the dynamical mean-field approximation and we study properties of the solution. We recover the correct three-peak density of states including the Kondo resonance and prove that it has the correct exponential scaling with increasing interaction strength. Our approximate scheme is further extended to multi-orbital models. We explicitly solve the two-orbital single impurity Anderson model and the Hubbard model and calculate effects of the Hund exchange interaction and the crystal field.