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The purpose of this thesis is the atomic-scale simulation of the crystal-chemical and physical (phonon, energetic) properties of some strategically important minerals for structural ceramics, biomedical and petrological applications. These properties affect the thermodynamic stability and rule the mineral-environment interface phenomena, with important economical, (bio)technological, petrological and environmental implications. The minerals of interest belong to the family of phyllosilicates (talc, pyrophyllite and muscovite) and apatite (OHAp), chosen for their importance in industrial and biomedical applications (structural ceramics) and petrophysics. In this thesis work we have applicated quantum mechanics methods, formulas and knowledge to the resolution of mineralogical problems ("Quantum Mineralogy”). The chosen theoretical approach is the Density Functional Theory (DFT), along with periodic boundary conditions to limit the portion of the mineral in analysis to the crystallographic cell and the hybrid functional B3LYP. The crystalline orbitals were simulated by linear combination of Gaussian functions (GTO). The dispersive forces, which are important for the structural determination of phyllosilicates and not properly con-sidered in pure DFT method, have been included by means of a semi-empirical correction. The phonon and the mechanical properties were also calculated. The equation of state, both in athermal conditions and in a wide temperature range, has been obtained by means of variations in the volume of the cell and quasi-harmonic approximation. Some thermo-chemical properties of the minerals (isochoric and isobaric thermal capacity) were calculated, because of their considerable applicative importance. For the first time three-dimensional charts related to these properties at different pressures and temperatures were provided. The hydroxylapatite has been studied from the standpoint of structural and phonon properties for its biotechnological role. In fact, biological apatite represents the inorganic phase of vertebrate hard tissues. Numerous carbonated (hydroxyl)apatite structures were modelled by QM to cover the broadest spectrum of possible biological structural variations to fulfil bioceramics applications. / Scopo della presente tesi di dottorato è la simulazione su scala atomica delle proprietà cristallochimiche e fisiche di alcuni minerali di importanza strategica per applicazioni ceramiche strutturali, biomediche e petrologiche. Tali proprietà influenzano le caratteristiche di stabilità termodinamica e guidano fenomeni all’interfaccia minerale-ambiente, con importanti ricadute economiche, (bio)tecnologiche, petrologiche e ambientali. I minerali di interesse appartengono alla famiglia dei fillosilicati (talco, pirofillite e muscovite) e delle apatiti (idrossiapatite), scelti per la loro importanza in ambito industriale, biomedico e petrofisico. In questo lavoro di tesi abbiamo applicato metodi, formule e conoscenze della meccanica quantistica a problemi di natura mineralogica (“Mineralogica Quantistica”). L’approccio teorico scelto è la Density Fuctional Theory (DFT), adoperata insieme a condizioni periodiche al contorno per limitare la porzione di minerale in analisi alla sola cella cristallografica e al funzionale ibrido B3LYP. Gli orbitali cristallini sono stati simulati mediante una combinazione lineare di funzioni gaussiane (GTO). Le forze dispersive, importanti per la determinazione strutturale dei fillosilicati e non propriamente considerate dal metodo DFT puro, sono state incluse mediante una correzione semi-empirica. Inoltre, sono state calcolate le proprietà fononiche e meccaniche. L’equazione di stato, sia in condizioni atermiche, sia in un ampio intervallo di temperature, è stata ricavata mediante variazioni dei volumi di cella e approssimazione quasi-armonica. Alcune proprietà termo-chimiche dei minerali (capacità termiche isocora e isobara) sono state calcolate, in quanto di notevole importanza in ambito applicativo. Per la prima volta sono forniti grafici tridimensionali relativi a queste proprietà a diverse pressioni e temperature. L’idrossiapatite è stata studiata dal punto di vista strutturale e fononico per il ruolo ricoperto dal minerale in ambito biotecnologico. Infatti, l’apatite biologica rappresenta la fase inorganica dei tessuti duri degli organismi vertebrati. Sono stati realizzati numerosi modelli di (idrossi)apatite carbonatata per coprire il più ampio spettro di possibili variazioni strutturali biologiche per applicazioni bioceramiche.

The surface properties of minerals have important implications in geology, environment, industry and biotechnology and for certain aspects in the research on the origin of life. This research project aims to widen the knowledge on the nanoscale surface properties of chlorite and phlogopite by means of advanced methodologies, and also to investigate the interaction of fundamental biomolecules, such as nucleotides, RNA, DNA and amino acid glycine with the surface of the selected phyllosilicates. Multiple advanced and complex experimental approaches based on scanning probe microscopy and spatially resolved spectroscopy were used and in some cases specifically developed. The results demonstrate that chlorite exposes at the surface atomically flat terraces with 0.5 nm steps typically generated by the fragmentation of the octahedral sheet of the interlayer (brucitic-type). This fragmentation at the nanoscale generates a high anisotropy and inhomogeneity with surface type and isomorphous cationic substitutions determining variations of the effective surface potential difference, ranging between 50-100 mV and 400-500 mV, when measured in air, between the TOT surface and the interlayer brucitic sheet. The surface potential was ascribed to be the driving force of the observed high affinity of the surface with the fundamental biomolecules, like single molecules of nucleotides, DNA, RNA and amino acids. Phlogopite was also observed to present an extended atomically flat surface, featuring negative surface potential values of some hundreds of millivolts and no significant local variations. Phlogopite surface was sometimes observed to present curvature features that may be ascribed to local substitutions of the interlayer cations or the presence of a crystal lattice mismatch or structural defects, such as stacking faults or dislocation loops. Surface chemistry was found similar to the bulk. The study of the interaction with nucleotides and glycine revealed a lower affinity with respect to the brucite-like surface of chlorite.