Localization of normal modes in vitreous silica, germania and beryllium fluoride
- 1 October 1970
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 3 (10) , 2111-2118
- https://doi.org/10.1088/0022-3719/3/10/013
Abstract
The authors previously (1968) presented vibrational spectra for vitreous silica, germania and beryllium fluoride, calculated from atomic arrangements in physical models based on the random network theory. The present work describes the localization properties of the normal modes of vibration. It is shown that the vibrations are, on the whole, less extended in space than the plane wave-like modes which characterize regular crystals. Localization tends to be greatest at high frequencies and, especially, near band edges. If nonbridging oxygen atoms are present in the structure, the spectra of vitreous silica and germania exhibit an additional band of very intense localization; atomic motions associated with modes in this band are effectively restricted to no more than a few atoms.Keywords
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