Transverse and longitudinal vibrations in amorphous silicon

17th Russian Youth Conference on Physics and Astronomy

物理学;天文学

Beltukov, Y.M.^1,2 ; Fusco, C.^3 ; Tanguy, A.^3 ; Parshin, D.A.^4

A. F. Ioffe Physical-Technical Institute, Saint-Petersburg

194021, Russia^1

Université Montpellier II, CNRS, Montpellier

34095, France^2

Université Lyon 1, Villeurbanne Cedex

F-69622, France^3

Saint Petersburg State Polytechnical University, Saint-Petersburg

195251, Russia^4

关键词: Frequency intervals;    Frequency ranges;    Harmonic vibration;    Longitudinal components;    Longitudinal vibrations;    Orthogonal components;    Transverse components;    Vibrational density of state;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/661/1/012056/pdf
DOI  :  10.1088/1742-6596/661/1/012056

学科分类：天文学(综合)

来源: IOP

【 摘 要 】

We show that harmonic vibrations in amorphous silicon can be decomposed to transverse and longitudinal components in all frequency range even in the absence of the well defined wave vector q. For this purpose we define the transverse component of the eigenvector with given ω as a component, which does not change the volumes of Voronoi cells around atoms. The longitudinal component is the remaining orthogonal component. We have found the longitudinal and transverse components of the vibrational density of states for numerical model of amorphous silicon. The vibrations are mostly transverse below 7 THz and above 15 THz. In the frequency interval in between the vibrations have a longitudinal nature. Just this sudden transformation of vibrations at 7 THz from almost transverse to almost longitudinal ones explains the prominent peak in the diffusivity of the amorphous silicon just above 7 THz.