VIBRATIONAL DYNAMICS AND RAMAN-SCATTERING IN FRACTALS - A NUMERICAL STUDY

The vibrational dynamics and Raman coupling coefficient of site percolating structures have been studied numerically. The main results that emerge from this work are the following: (i) Characterization of fractons in k space clarifies the oscillatory nature of the modes and allows an average wavelength to be defined, which is more correlated with frequency than the localization length, which fluctuates strongly; (ii) in these systems, it is not easy to define a local strain due to their essentially disordered structure; (iii) the Raman coupling coefficient C(omega) was calculated in the dipole-induced-dipole and bond-polarizability approximations. The scaling laws proposed so far for C(omega) do not reproduce the results of our simulation; the difficulty of finding a scaling law in terms of the fractal macroscopic parameters is discussed.