The WURM project - a web-based freely available database of computed physical properties for minerals

Teaching of vibrational spectra for minerals is highly improved by visual media support. The atomic vibrations are usually described by words such as breathing, symmetric or asymmetric stretching, bending, rolling and so on. However only the visualization of these modes can bring a thorough understanding of the dynamics of a crystalline lattice. Here we present the WURM database, whose aim is to build a freely accessible web-based repository of computed physical properties for minerals. Apart from the crystal structure used in the calculation, the dynamical charges and the dielectric tensors, and the refractive index, the WURM database presents at length the Raman spectra with both peak position and intensity and the infrared peak positions. In fact the vibrational information makes the bulk of the database and constitutes the major computational effort. For each vibrational mode in the zone-center we determine the frequency, the symmetry assignment, the atomic displacement patterns, and the Raman tensors. The database is freely available on the web at http://www.wurm.info and is highly interactive. Jmol-powered applets incorporated in the website allow the quick visualization of the crystal structure and of the atomic displacement patters of all vibrational modes. All the results are exclusively obtained from first-principles calculations performed using the local density approximation of density functional theory and density functional perturbation theory in the ABINIT implementation [http://www.abinit.org], based on planewaves and pseudopotentials.