First-principles modeling of the infrared spectrum of antigorite
2021
Abstract. The infrared absorption spectrum of a natural antigorite sample from New
Caledonia is compared to its theoretical counterpart computed for the
pristine antigorite m=17 polysome within the density functional
perturbation theory framework. The theoretical model reproduces most of the
bands related to Si-O stretching in the 800–1300 cm−1 range, OH
libration, hindered OH translation and SiO 4 bending in the 400–800 cm −1 range, and OH stretching in the 3500–3700 cm−1 range.
Most of the observed bands have a composite nature involving several
vibrational modes contributing to their intensity, except the apical and one
of the basal Si-O stretching bands whose intensity is carried by a single
mode. The peculiarity of the antigorite structure favors a localization of
the Si-O and OH stretching modes in specific regions of the unit cell.
Weaker Si-O stretching bands experimentally observed at 1205 and 1130 cm −1 are related to the occurrence of 6- and 8-reversals in the
antigorite structure, respectively. The distribution of OH bond lengths
leads to an asymmetric distribution of frequencies consistent with the width
and the shape of the experimentally observed OH stretching band. It also
leads to a strong distribution of OH libration frequencies ranging from 600
to 830 cm−1 explaining the asymmetry of the band observed at 648 cm −1 in the antigorite spectrum.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
47
References
2
Citations
NaN
KQI