Abstract
We discuss the ground-state energy of the Anderson degenerate impurity model for both finite and infinite on-site Coulomb repulsion U. The goal of the paper is to demonstrate the applicability of a theoretical approach to static ground-state properties introduced recently. This approach is based on the projection technique and on the introduction of cumulants. It allows for proper treatment of strong electronic correlations that are incorporated in the model. It also guarantees the size consistency of the evaluated physical quantities. We start from a compact expression for the ground-state energy, which is expanded into a continued fraction. By summing up the infrared divergencies, a self-consistent equation for the ground-state energy is found. For degeneracy Nf and U the equation can be solved rigorously and gives the well-known Varma-Yafet solution. For Nf and U both finite our procedure leads to the result of the variational approach of Gunnarsson and Schönhammer.
Original language | English |
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Pages (from-to) | 6062-6072 |
Number of pages | 11 |
Journal | Physical Review B |
Volume | 44 |
Issue number | 12 |
DOIs | |
State | Published - 1991 |