Singularities of a mean field Green's function

A mean field approximation allows microscopic calculations of an N-body propagator G(z) = (z-H)-1. We investigate singularities of the resulting approximate Green's function, Gmf(z), by comparing them to the binding energies calculated by the Hartree-Fock approximation. We show that each Hartree-Fock energy induces a singularity of Gmf. (author)