Vibrational behavior of a realistic amorphous-silicon model

The vibrational properties of a high-quality realistic model of amorphous silicon are examined. The longitudinal and transverse dynamical structure factors are calculated, and fitted to a damped harmonic oscillator (DHO) function. The width Γ of the best-fit DHO to the longitudinal dynamical structu...

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Bibliographic Details
Published in:Journal of non-crystalline solids 2007-07, Vol.353 (22), p.2272-2279
Main Authors: Christie, J.K., Taraskin, S.N., Elliott, S.R.
Format: Article
Language:English
Subjects:
Condensed matter: structure, mechanical and thermal properties
Exact sciences and technology
Lattice dynamics
Molecular dynamics
Phonons
Physics
Silicon
Vibrational states in disordered systems
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Summary:The vibrational properties of a high-quality realistic model of amorphous silicon are examined. The longitudinal and transverse dynamical structure factors are calculated, and fitted to a damped harmonic oscillator (DHO) function. The width Γ of the best-fit DHO to the longitudinal dynamical structure factor scales approximately as k 2 for wavevectors k ≲ 0.55 Å −1, which is above the Ioffe–Regel crossover frequency separating the propagating and diffusing regimes, occurring at k = 0.38 ± 0.03 Å −1. Using the DHO function as a fitting function for the transverse dynamical structure factor (without theoretical justification), gives a dependence of Γ ∝ k α with α ∼ 2.5 for wavevectors k ≲ 0.7 Å −1. There was no evidence for Γ ∝ k 4 behavior for either polarization.
ISSN:0022-3093
1873-4812
DOI:10.1016/j.jnoncrysol.2007.02.039