A new method for the Raman spectra calculation of binary silicate melts: application to the calcium silicate

Abstract: This contribution gives a newly deduced method for the Raman spectra calculation of molten silicates. This method essentially combines MD simulation, GF matrix method, electro-optical parameters method (EOPM), and bond polarizability model (BPM). For the sake of proof, a simple application for the CaO-SiO2 melt of this method is performed and compared with experiments. To interpret the experimental Raman spectra of vitreous and molten silicate in depth, theoretical understanding of the vibrational properties of silicate is indispensable. Up to now many researchers have concentrated to this field, e.g. Sen and Thorpe [1], Garofalini [2], Gaskell [3], Bell and Hibbins-Butle [4], Brawer [5], Furukawa & Fox & White [6], Dowty [7], and Zotov et al.[8]. Summary of their works can achieve a uniform character when applying the calculation to the disordered system that the broadening of all calculated bands was artificial but not authentic. As we know, the full widths of half maximum (fwhm) of the bands are directly related with the disorder degree of system, i.e. the distribution of the structural properties. Thus, we developed a new special method or called routine for the Raman spectra calculation of amorphous silicates, which broadens the calculated bands automatically. Firstly, classical molecular dynamics (MD) simulation is performed to obtain thousands of equilibrium configurations, which will be decomposed into five kinds of Si-O tetrahedra as defined in Fig. 1, which are denoted as Qi which subscript i represents the number of bridging oxygen.