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Vibrational behaviour of a realistic amorphous-silicon model

J. K. Christie·S. N. Taraskin·S. R. Elliott
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Abstract

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 $k\lesssim0.55\textrmÅ^{-1}$, which is above the Ioffe-Regel crossover frequency separating the propagating and diffusing regimes, occurring at $k=0.38\pm0.03\textrmÅ^{-1}$. Using the DHO function as a fitting function for the transverse dynamical structure factor (without theoretical justification), gives a dependence of $Γ\propto k^α$ with $α\sim2.5$ for wavevectors $k\lesssim0.7\textrmÅ^{-1}$. There was no evidence for $Γ\propto k^{4}$ behaviour for either polarization.

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J. K. Christie, S. N. Taraskin, S. R. Elliott. 2007-01-09. Vibrational behaviour of a realistic amorphous-silicon model. https://doi.org/10.1016/j.jnoncrysol.2007.02.039

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