The packing structure of three unit cells for (a) and the model cluster used in the ab initio calculation of vibrational states (b).
The Raman scattering spectra (upper) and the FTIR transmission spectra (lower) of the pure . The Raman lines selected for listing in Table I are denoted by the arrows. The data for the graphs were taken from Ref. 13 with the permission from those authors.
The simulated IR and Raman spectra for the cluster as obtained from the ab initio calculation using the unrestricted spin HF SCF model with 3-21G basis set.
Two phases of the O(2) vibration along axis in the forbidden Raman shift (a) and the phases of the O(1) parallel movement along together with the O(2) stretching motion in plane in shift (b).
The Raman and IR frequencies for . Comparisons are given to the pure (Ref. 11), the Sr-doped (Refs. 10 and 11) and to the theoretical values obtained by the lattice dynamic calculation (Refs. 11). and the tight-binding approach (Ref. 14). For the Raman-forbidden lines, the values presented in parentheses correspond to the additional features visible in Fig. 4 in Ref. 10 but not reported by its authors.
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