De Gennes correlation function method applied to electron gas problems

The authors show that the RPA polarization function is simply related to the classical correlation function for motion of electrons at the Fermi surface which was introduced by De Gennes for problems in superconductivity. The method gives a very direct derivation of the bulk plasma frequency and the Debye screening length, and of the surface plasmon frequency. The authors apply it in addition to obtain the static screening and plasmon linewidth for an alloy with a scattering time tau <<1/ omega p.