Why have the Vibrational Frequency Spectra of Disordered Chains Many Distinct Peaks?

Abstract

By using the vector picture introduced previously, it is shown that disordered diatomic chains with sufficiently large mass-ratio have very strong tendency to have eigenfrequencies which are close to those of localized modes produced by several types of islands containing light atoms imbedded in a regular lattice composed of heavy atoms. This explains why the vibrational frequency spectra of disordered chains have in general very complicated structures with many well-defined peaks.