  Theory of the first order Raman scattering (FOR) line shape allowing for
nonlinear and correlation effects contribution to inhomogeneous broadening as
well as dynamic mechanisms of homogeneous broadening is developed. It is shown
that in general case FOR line contains two maxima, shape of low frequency one
being defined by homogeneous broadening. Our theory explains the peculiarity of
observed FOR scattering of TO_2 hard phonon in KTL and KTN at different
temperatures and concentrations of Li and Nb ions.
