Applicazine di strumenti computazionali allo studio di solidi

The present thesis work spans over three different projects that were the most im- portant part of my didactic process in the last years. For the sake of learning how to perform solid state simulation, when I started the thesis project, I was inserted in the study of defects in diamond. Since it was the first time I was performing calculation in that occasion I learnt how to collect and analyse computational data. After the study of basic computational tools as geometry optimisation and frequency calculation I started to study simple magnetic properties as electron paramagnetic resonance parameters and magnetic dipoles in interstitial diamond defects. Thanks to this study new data analysis tools were used and added to my skills. After all the diamond defects related research I studied more interesting magnetic properties in other ionic materials as perowskites and other fluorides. The last topic I investigated was an application of the knowledge acquired, in fact the project on ITO was not present in the theoretical chemistry group before I started it. In the last project a com- plete electronical characterisation of INO and ITO is provided with peculiar focus on the band structure and the band gap determination through different computational methods and settings. The thesis is structured as follows: in the first chapter a brief introduction on the investigated materials is provided with focus on their properties an applications (diamond, perowskites, transition metal fluorides, indium oxide and indium tin oxide); in the second chapter the computational parameters adopted are shown with brief theoretical explanation of the algorithms; in the third chapter the investigation of substitutional nitrogen and boron in diamond is used as case study to explain the common computational strategy adopted in material studies; in the fourth chapter the EPR investigation of interstitial carbon and nitrogen defects in diamond is reported with all the computed data in comparison with the experimen- tal ones; in the fifth chapter ferromagnetism and anti-ferromagnetism properties of perowskites and transition metals fluoride are reported and compared with exper- imental results; in the sixth chapter are reported the first steps and the first results of the indium oxide and indium tin oxide investigation with computational data in comparison with experimental ones and a brief overview on the continuation of the project.