TY - JOUR
T1 - Origin of the high-frequency doublet in the vibrational spectrum of vitreous SiO2
AU - Sarnthein, Johannes
AU - Pasquarello, Alfredo
AU - Car, Roberto
PY - 1997/3/28
Y1 - 1997/3/28
N2 - The vibrational properties of amorphous SiO2 were studied within first- principles density functional theory. The calculated spectrum is in good agreement with neutron data, showing, in particular, a double peak in the high-frequency region. This doublet results from different local modes of the tetrahedral subunits and cannot be ascribed to a longitudinal-optic- transverse-optic (LO-TO) effect. This solves a long-standing controversy about the origin of the doublet in neutron spectra. A LO-TO splitting is recovered only when the long-wavelength limit is probed, as in optical experiments. These findings should be a general feature of tetrahedral AX2 amorphous networks.
AB - The vibrational properties of amorphous SiO2 were studied within first- principles density functional theory. The calculated spectrum is in good agreement with neutron data, showing, in particular, a double peak in the high-frequency region. This doublet results from different local modes of the tetrahedral subunits and cannot be ascribed to a longitudinal-optic- transverse-optic (LO-TO) effect. This solves a long-standing controversy about the origin of the doublet in neutron spectra. A LO-TO splitting is recovered only when the long-wavelength limit is probed, as in optical experiments. These findings should be a general feature of tetrahedral AX2 amorphous networks.
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U2 - 10.1126/science.275.5308.1925
DO - 10.1126/science.275.5308.1925
M3 - Article
C2 - 9072968
AN - SCOPUS:0030936322
SN - 0036-8075
VL - 275
SP - 1925
EP - 1927
JO - Science
JF - Science
IS - 5308
ER -