Harmonic vibrational excitations in graded elastic networks: transition from phonons to gradons

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We have identified a new type of transition from extended to localized vibrational states in one-dimensional graded elastic chains of coupled harmonic oscillators, in which the vibrating masses or nearest-coupling force constants vary linearly along the chain. We found that the delocalization transition occurs at the maximum frequency of the corresponding homogeneous chain, which is in a continuous single band. Although each state in the localized phase, called gradon, can be regarded as an impurity localized mode, the localization profile is clearly distinct from usual impurity modes or the Anderson localized modes. We also argue how gradons may affect the macroscopic properties of graded systems. Our results can provide insights into many analogous systems with graded characters.
LaTeX format, 7 eps figures, submitted for publications

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Materials Science, Disordered Systems and Neural Networks, Computational Physics

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http://salesiana.dossiersoluciones.com/handle/123456789/105502

Consulte el texto completo en el siguiente enlace:

https://arxiv.org/abs/cond-mat/0512149
 http://arxiv.org/abs/cond-mat/0512149
 Phys. Rev. B 73, 054201 (2006)
 doi:10.1103/PhysRevB.73.054201 10.1103/PhysRevB.73.224201

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arXiv