Selfconsistent effective interactions and symmetry restoration

In this paper we propose a general framework for deriving the effective interactions for many-body systems. We show how the selfconsistent interaction can be constructed on the quantum level for both local and nonlocal potentials. In particular the relation between the selfconsistent and symmetry restoring interaction is derived. The difference between the two is related to the coupling of the perturbing field to the kinetic energy operator.