Abstract:The Raman spectra of several typical crystals of alkali fluoroaluminate system were studied. Ab initio calculation of quantum chemistry was used to construct several super molecule model clusters. Restricted Hatree-Fock method (RHF) with the basis set of 6-31G(d) was applied to optimize the geometry of fluoroaluminate model clusters. The wavenumbers of Raman-active modes and Raman optical activity (ROA) were calculated under the same method with the same base set after geometric optimization. The calculation results were compared with the experimental data. The results show that the delicate variation of micro-environment or super molecular number can be correctly resolved by Raman shift. That is, the calculated Raman wavenumber of Al—F symmetric stretching vibration is much closer to experimental data when super molecular number gradually increases.

Key words: fluoroaluminate; model clusters; micro environment; Raman spectra