An induced interaction model for arbitrarily polarized Fermi systems

• DOI: 10.1007/bf00682568
• Publication Date: 2004-11-28T13:09:51Z
• Authors: K. F. Quader; K. S. Bedell
• Keywords: Diagrammatic reasoning

A model for calculating the interactions in arbitrarily spin-polarized Fermi systems is presented. Starting from the four-point vertex functions, the “induced” part of the interactions is deduced by explicitly treating the one-particle, one-hole irreducible diagrams and using some general crossing symmetry relations. Extrapolation away from the Fermi surface is carried out by replacing the particle-hole phase space by Lindhard functions in the “crossed” channel; consequently, calculation of the necessary ↑-↓ phase space function is presented. The longitudinal spin-density and density responses for polarized systems are obtained by diagrammatic means. A possible way of treating the “direct” part of the interactions using Born approximation is also discussed. Finally, the limits of the model for zero and full polarization are given.