PbO2 is one material that has recently emerged as potential transparent conducting oxide for applications in the modern opto-electronic industry. In this work the electronic structure of the α-PbO2 polymorph has been investigated, aiming to contribute to the understanding of its high levels of conductivity. DFT calculations using B3LYP hybrid density functional and considering long range interactions among the atoms have been performed. A direct band gap of 0.90 eV has been found, compatible with high conductivity values. Although the stoichiometric material is somewhat transparent, the band structure indicates that appropriated modifications in the material Fermi level can be performed in order to decrease the absorption of light. Charge distribution plus overlap population analysis show that the material is predominantly ionic. The charge distribution throughout the material is strongly dependent on the crystal direction. Results suggest that α-PbO2 can be potentially more interesting for opto-electronic purposes than the β polymorph.

Computational simulations based on periodic density functional theory have been carried out to investigate the control of crystal morphology by accurate values of surface energies by Wulff theorem. This method can be used as a very useful tool for the design and knowledge of synthesis of new materials. In a special case, rutile TiO2 phase, exhibits great variety of morphologies and properties making this system an interesting target for this approach. The low index, (100), (001), (101), (110), (111) surfaces were modeled and the respective surface energies produces the follows stability order: (110) < (010) < (101) < (001) < (111). The map of some morphologies routes was constructed from the calculated energies as a starting point without environmental influence and can be used to elucidate the influence of chemical routes. This method has helped in the knowledge of morphological modifications as a function of synthesis environment besides the connection between system characteristics and the exposed surfaces.

The absorption edge and the bandgap transition of sol-gel-dip-coating SnO2 thin films, deposited on quartz substrates, are evaluated from optical absorption data and temperature dependent photoconductivity spectra. Structural properties of these films help the interpretation of bandgap transition nature, since the obtained nanosized dimensions of crystallites are determinant on dominant growth direction and, thus, absorption energy. Electronic properties of the bulk and (110) and (101) surfaces are also presented, calculated by means of density functional theory applied to periodic calculations at B3LYP hybrid functional level. Experimentally obtained absorption edge is compared to the calculated energy band diagrams of bulk and (110) and (101) surfaces. The overall calculated electronic properties in conjunction with structural and electro-optical experimental data suggest that the nature of the bandgap transition is related to a combined effect of bulk and (101) surface, which presents direct bandgap transition.

The electronic, structural properties and elastic constants of the wurtzite phase of zinc oxide, ZnO, was investigated using computer simulation at Density Functional Theory level, with B3LYP hybrid functional and Hartree-Fock methodology. The electronic properties as well the band energy was investigated through the analysis of the band structures and density of states (DOS), and the mechanical properties was studied through the calculus of the elastic constants C11, C33, C44, C12 e C13. The results are in good agreement with experimental data found in the literature and in accordance with results obtained by another theoretical methodology.

A computational method to simulate the changes in the electronic structure of Ga1-xMn xN was performed in order to improve the understanding of the indirect contribution of Mn atoms. This periodic quantum-mechanical method is based on density functional theory at B3LYP level. The electronic structures are compared with experimental data of the absorption edge of the GaMnN. It was observed that the indirect influence of Mn through the structural parameters can account for the main part of the band gap variation for materials in the diluted regime (x<0.08), and is still significant for higher compositions (x~0.18).