Phonons in vitreous silica: Dispersion and localization
Department of Chemistry, University of Cambridge,
Lensfield Road, Cambridge CB2 1EW, UK
Accepted: 29 May 1997
A numerical vibrational-mode analysis has been performed for structural models of vitreous silica constructed using molecular dynamics. Dispersion curves, associated with remnants of phonon-like behaviour, exhibit pseudo-zone boundaries revealing evidence for two pseudo-periods in the structure, the dominant one being equal to the height of tetrahedra, and the other to the corresponding height of tetrahedra. A new model for the boson peak is proposed: the excess modes are the lowest optic band states hybridized with acoustic states.
PACS: 61.43.Bn – Structural modeling: serial-addition models, computer simulation / 61.43.Fs – Glasses / 63.50.+x – Vibrational states in disordered systems
© EDP Sciences, 1997