Vibrational spectra of diatomic chains

Abstract

Quantitatively accurate results for the vibrational spectra of disordered diatomic chains have been computed for four systems over a complete range of lattice order. The spectra obtained are far more complex than has hitherto been suspected, a most detailed array of peaks and valleys becoming apparent for the completely disordered chain at a mass ratio of about 2. The theory of defect modes in nearly ordered lattices shows the association of a number of the peaks with particular kinds of localized chain structure and points the way to possible developments for three-dimensional systems.