Green functions in low-energy nuclear physics

The response of a system in its ground state to an external perturbation can be described in terms of Green functions. The formal properties of such Green functions are described, and methods of calculating them are given. It is shown how such methods have been applied to various problems in nuclear physics, and some further possible applications are indicated. The theory of nuclear matter, the foundations of the optical model and the theory of nuclear collective motion are considered, and it is shown how the methods can be modified to allow for the influence of pairing forces by techniques borrowed from the theory of superconductivity.