Phase and amplitudon-like vibrations of one dimensional inconmesurate systems.

Abstract

In this paper we show that phason- and amplitudon-like vibrations can be obtained in one-dimensional incommensurate systems with harmonic interactions between first neigh bours only. This is achieved provided a realistic modulation of the force constants is used. The incommensurate systems are approximated by commensurate ones with large unit cells. Several criteria are used to characterise the phason- and amplitudon-like vibrations and we find that these types of vibrations exist, for reasonable values of the amplitude of the modulation. if there is a sufficient number of atoms per modulation period.