Vibrational modes in harmonic chains with diluted disorder

We study the nature of collective excitations in harmonic chains with diluted disorder. Using a transfer matrix method, we compute the localization length of eigenmodes within the band of allowed energies in order to investigate the new extended states which appear in this model. To follow the time...

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Bibliographic Details
Published in:Physica A 2005-11, Vol.357 (1), p.165-172
Main Authors: Albuquerque, S.S., de Moura, F.A.B.F., Lyra, M.L.
Format: Article
Language:English
Subjects:
Anomalous diffusion
Localization
Vibrational modes
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Summary:We study the nature of collective excitations in harmonic chains with diluted disorder. Using a transfer matrix method, we compute the localization length of eigenmodes within the band of allowed energies in order to investigate the new extended states which appear in this model. To follow the time evolution of an initially localized energy input, we calculate the second moment M 2 ( t ) of the energy spatial distribution. We found that for an impulse initial excitation, the super-diffusive energy spread is not affected by the presence of new resonant modes. However, the energy spread becomes faster for a displacement excitation.
ISSN:0378-4371
1873-2119
DOI:10.1016/j.physa.2005.05.059