Chair of solid state physics . ... One-particle Green’s function (Non interacting fermions) . Verbal definition of retarded one-particle Green’s function. ... One-particle Green’s function (Interacting fermions) . Formal definition of one-particle Green’s function. ... Quasi particles in Hartree-Fock approximation. ... Quasi particles and one-particle Green’s function. ... Vertex function and scattering of quasi particles. ... Matsubara Green’s function foe free particles. ...