More on the frequency spectrum of an artificial amorphous solid

In a previous paper on the same subject an analysis of the frequency spectrum of an amorphous Lennard-Jones solid, as determined by methods of molecular dynamics by Rahman and collaborators, was given. There the general form of the spectrum was considered. Here it is shown how the analysis of the spectrum can be refined so as to allow a separation of the contribution of the propagating waves from the contribution of that fraction of atomic oscillations that do not possess propagational character. It is thus possible to bring indirectly into evidence bands of transverse and longitudinal waves, contributing a nonnegligible fraction of atomic motion