Ab initioRaman spectrum of the normal and disorderedspinel
- 31 October 2006
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 74 (14), 140301
- https://doi.org/10.1103/physrevb.74.140301
Abstract
Ab initio calculations, based on density functional theory, of the vibrational Raman spectra of both normal and cationic disordered spinel are reported. The vibrational properties of the disordered system are obtained in two steps. First, the interatomic force constants of small defective supercells are computed in a fully ab initio way. Later, these force constants are used to build the dynamical matrices of larger disordered systems. The calculated Raman spectrum presents the mode near which is due to the presence of cationic disorder and which is commonly attributed to a breathing mode (BM) of tetrahedra. Contrary to previous interpretations, the mode is due to phonons which are silent in the perfect crystal and become Raman active in the disordered structure because of the coupling with the BM of the tetrahedra.
Keywords
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