Phonon Dynamics in Superconductors

Abstract

A theory of phonon dynamics of superconductors is presented on the basis of a Hamiltonian which includes the bare Coulomb interaction term and the bare ion frequency term. A diagram method which corresponds to the random phase approximation is adopted. This theory can provide a basis for discussions of anomalies of the phonon structure. In connection with anomalous aspects of phonon dynamics there exist several works in which anomalies directly reflect the singular behavior of the proper polarization function of the density fluctuation in the superconducting case. These works are criticized through our theory.