Detailed crystallographic information provided by X-ray diffraction (XRD) is complementary to molecular information provided by Raman spectroscopy. Accordingly, the combined use of these techniques allows the identification of an unknown compound without ambiguity. However, a full combination of Raman and XRD results requires an appropriate and reliable reference database with complete information. This is already available for XRD. The main objective of this paper is to introduce and describe the recently developed Raman Open Database (ROD, http://solsa.crystallography.net/rod). It comprises a collection of high-quality uncorrected Raman spectra. The novelty of this database is its interconnectedness with other open databases like the Crystallography Open Database (http://www.crystallography.net/cod and Theoretical Crystallography Open Database (http://www.crystallography.net/tcod/). The syntax adopted to format entries in the ROD is based on the worldwide recognized and used CIF format, which offers a simple way for data exchange, writing and description. ROD also uses JCAMP-DX files as an alternative format for submitted spectra. JCAMP-DX files are compatible to varying degrees with most commercial Raman software and can be read and edited using standard text editors.

The temperature and chemical dependence of the melt viscosity are ubiquitous in the model development of the volcanic dynamics, as well as in the glass production and design. We focussed on the yet-explored relationship between the bulk and shear moduli ratio and boson peak with the melt fragility of their parental glasses. Here, we explored the extension of the observed trend by testing the conventional binary system Na₂O-SiO₂, thus providing new evidence supporting the link between the flow of melts and supercooled liquids and the vibrational dynamics of their parental glasses. This was accomplished by integrating new low-frequency Raman measurements and integrating data from the literature on Brillouin light scattering and viscometry. This approach allows us to feed the MYEGA equation with reliable input parameters to quantitatively predict the viscosity of the Na₂O-SiO₂ system from the liquid up to the glass transition.

We investigated the structure of pure and Sc-doped synthetic diopside (a monoclinic single-chain silicate nominally CaMgSi₂O₆); in Sc-doped diopside, Sc³⁺ substitutes Mg²⁺ in the structure and, to achieve charge balance, vacancies form at the expense of Ca²⁺. We compared the structure obtained from ab initio modelling techniques at the density functional theory (DFT) level with the structure solved by employing single crystal X-ray diffraction. Furthermore, we compared IR and Raman spectroscopy experiments with vibrational density of states (VDOS) calculated from the Fourier transform of the velocity autocorrelation function obtained using ab initio (DFT) molecular dynamics simulations. In this framework, we developed a computational tool to assign the vibrational mode associated with a specific frequency. This method consists of projecting velocities along a specific set of internal coordinates such as stretching or bending, in cases involving defects or vacancies, to calculate a partial VDOS (pVDOS) that takes into account only the vibrations associated with selected internal modes, aiding the interpretation of the total VDOS and the experimental spectra in a relevant way. The computed data were validated with the experiments and we observed that doping the diopside structure with Sc produces peak broadening and the occurrence of new peaks in the Raman spectra and that site vacancies are associated with the nearby Sc site. The present work constitutes an interesting starting point to exploit the calculated VDOS/pVDOS to characterize experimental vibrational spectra of complex systems containing local vacancies, substitutions or defects as the Sc-doped diopside.