Abstract

The vibrational properties of vitreous silica are discussed in light of recent results obtained using a first-principle approach. The high-frequency doublet appearing in the inelastic neutron spectrum results from different local modes of the tetrahedral subunits and is not related to the longitudinal-optic-transverse-optic (LO-TO) splitting observed with infrared spectroscopy. The highest energy component of this doublet is suppressed in infrared spectra, which show a marked LO-TO splitting associated to the lowest energy component of the doublet.

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