Applications of computational methods to minerals and materials : vibrational spectroscopy and low dimensional structures

Orateur : Marco DE LA PIERRE

Development of methods in computational chemistry has nowadays reached very high levels of performance in terms of both accuracy and required computing resources. As a consequence, these techniques have become an invaluable instrument to investigate condensed matter with a possible focus on a multitude of different aspects. Relevant examples will be discussed in this seminar, covering a variety of methods and subjects of study. Vibrational spectroscopy, both infrared and Raman, is a powerful tool for the characterisation of solid state, as it is very sensitive to the features of the electronic potential, and then capable of exploring a range of aspects including composition (chemical and isotopic), crystalline phase, symmetry. “Ab initio” computational spectroscopy, alone or in synergy with the experiments, can be applied effectively to interpret observations and to validate hypotheses that result from laboratory research [1]. Based on density functional theory (DFT) and on hybrid Hartree-Fock/DFT methods, practical examples comprehend spectral analysis through combined simulations and experiments [2], effects of composition and disorder in solid solutions [3], polymorphism in calcium carbonate [4]. Low dimensional structures are often the main responsible for the properties and behaviours of interest in materials in the fields of geochemistry and technology. As an example, nucleation and growth of minerals in aqueous solution are crucially related to the phenomena occurring at the interface between the mineral surface and the liquid phase. In this context, classical molecular dynamics and free energy calculations can be adopted to investigate the structure, dynamics and thermodynamics of these systems [5]. Other examples are fullerenes and chrysotile, two materials of technological and geological interest whose building units are molecules and nanotubes, respectively, of varying size. In this case “ab initio” electronic structure calculations allow for the analysis of structural, electronic and stability properties as a function of the size, for radii up to hundreds of angstroms (thousands of atoms), as well as in comparison with similar materials featuring higher dimensionality [6,7].

Télécharger dans mon agenda