  The "density-density" correlation function of conduction electrons in metal
is investigated. It is shown, that the asymptotic behaviour of the CF depends
on the shape and the local geometry of the Fermi surface. In particular, the
exponent of power law which describes the damping of Friedel oscillations at
large r (-4 for an isotropic Fermi gas) is determined by local geometry of the
FS. The applications of the obtained results to calculations of the CF in a
metal near the electron topological transition and of the RKKY exchange
integral are considered as well.
