Localization in a topologically disordered chain

Vibrational spectra and displacement eigenvectors have been obtained for a topologically disordered linear chain in which all atomic masses and force constants are taken to be identical, but the interatomic linkages are selected on a random basis. It is found that this topological disorder, no less than other kinds of disorder discussed in the literature, can lead to appreciable mode localization over most of the frequency range. Attention is drawn to a special class of topologically disordered chains in which the vibrational modes near the centre of the spectral band are strongly localized, while those at the band edges are of an extended wavelike character.