This article is cited in 14 papers

Lattice dynamics

Spontaneous excitation of discrete breathers in crystals with the NaCl structure at elevated temperatures

A. A. Kistanov, S. V. Dmitriev

Institute for Metals Superplasticity Problems of RAS, Ufa

Abstract: The density of phonon states at various temperatures has been calculated for crystals with the NaCl structure with equal and strongly differing weights of anions and cations. It has been shown that, in the crystal with a considerable difference in the weights of components, a wide band gap exists in the spectrum of phonon states, which leads to spontaneous excitation of nonlinear localized vibrational modes–gap discrete breathers having frequencies inside the band gap, if the temperature is sufficiently high. It has been found that the peak of the density of phonon states lying above the spectrum of linear vibrations appears at elevated temperatures, which can indicate the existence of discrete breathers with corresponding frequencies. It has been noted that, previously, the existence of gap discrete breathers in the NaI crystal at 555 K was shown experimentally. The presented results bring up the question of the theoretical justification and experimental observation of the breathers with frequencies above the phonon spectrum.

Received: 01.02.2012

 English version: Physics of the Solid State, 2012, 54:8, 1648–1651

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