Anomalous sound propagation in a solid with a special acoustic phonon dispersion relation

We investigate a new type of solids which has a special acoustic phonon dispersion relation of ω = ak2 type. This has been partially observed in graphite. This type of solids usually has a mechanical instability under a homogeneous expansion or a homogeneous deformation and also has a thermal instab...

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Bibliographic Details
Published inJournal of physics. Conference series Vol. 92; no. 1; p. 012155
Main Authors Goda, M, Okamura, M, Nishino, S, Okui, S, Tanaka, R, Kudo, M
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 01.12.2007
Subjects
Acoustic propagation
Acoustics
Atomic interactions
Atomic properties
Boundary conditions
Computer simulation
Phonons
Physics
Sound propagation
Thermal instability
Wave dispersion
Wave propagation
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Summary:We investigate a new type of solids which has a special acoustic phonon dispersion relation of ω = ak2 type. This has been partially observed in graphite. This type of solids usually has a mechanical instability under a homogeneous expansion or a homogeneous deformation and also has a thermal instability. These instabilities can be eliminated by introducing a small cut-off wave number or a suitable unharmonic inter-atomic interaction. We remove the former one by introducing the periodic boundary condition. Some general features of the peculiar "solid" are investigated theoretically and numerically. Especially we investigate the anomalous wave propagation of the dispersive acoustic phonons numerically. The computer simulation of the wave–packet dynamics shows us a stronger localisation character than that in a normal solid in the case of 1-dimensional disordered systems.
ISSN:1742-6596
1742-6588
1742-6596
DOI:10.1088/1742-6596/92/1/012155