Green's functions and equations of motion in correlated many body systems

In this paper some new physical notations are given for the Green’s functions and equations of motion (EOM) in many body physics with the concept of quasiparticles. It shows how the many body correlations existing in many body systems can be taken into account through the derivation of EOMs self-consistently. The scheme is compared with the expansion of Feynman diagrams. Finally some further discussions are given for the unique properties of EOM techniques in helping to model a system and the interactions self-consistently.