Narrow Results

Density functional theory (DFT) and generalized gradient approximation (GGA) have been employed to study adsorption geometry and electronic properties of the system consisting of rutile (110) surface and dopamine molecule. Hubbard U-like term is included to consider more adequately 3d electrons of Ti atoms. Results indicate that dopamine adsorption takes place in a bidentate geometry by forming strong bonds between two molecular oxygens and two titaniums situated on the surface. Geometry changes of molecular atoms, as well as those constituting upmost layer of the surface has been discussed in detail. Reduction in the band-gap width due to the adsorption has been found implying potential interest of the system for light-harvesting solar cells.

First-principles calculations based on the density functional theory (DFT) within the generalized gradient approximation (GGA) have been used to study Sc-doped TiO₂, rutile and anatase, crystals. Local defect microstructure, electronic and electrical properties have been obtained and discussed in the present work. Large radius hole polaron state found here points out to the possibility of p-type electrical conductivity in Sc-doped titania.

A single Fe impurity impact on the properties of ZrSiO₄ low pressure phase (zircon) has been addressed in the present work. First-principles density functional theory and generalized gradient approximation have been exploited throughout the study. Strong electron correlation effects not included in the density-functional formalism are treated by a Hubbard-type on-site Coulomb repulsion approach. Our results provide evidence over occurrence of a local magnetic moment in the material. Reduction in the band-gap width, changes in chemical bonding and microstructure of the defective region have been discussed as well.

Study of corundum-type chromium oxide ($\alpha$-Cr₂O₃) crystal doped with the nitrogen and magnesium impurities has been carried out through the use of first-principles calculations based on the density functional theory (DFT) and generalized gradient approximation (GGA). Three cases corresponding different impurity–impurity distances have been considered. Structural, electronic and magnetic properties have been studied for all co-doping cases. The $p$-type electrical conductivity was found when distance between the Mg and N atoms is equal to 4.10 Å. The results obtained are consistent with the available experimental data.

The superconductivity and magnetic phenomena of the rare earth iron pnictides RFePO (R = La, Sm) are analyzed using ab initio density functional theory in the local density approximation (LDA) with the on-site Hubbard U_eff parameter (LDA + U). The results of the magnetic properties, band structures and Fermi surfaces of the recently synthesized tetragonal layered iron pnictides superconductor SmFePO are presented in comparison with the superconductor LaFePO. The anti-ferromagnetic state [Sm: AFM, Fe AFM_stripe] is found to be the most stable than the other possible phases, which is in agreement with experiment. The effect of the Hubbard correction is investigated and is found to be a necessary requirement for the accurate description of both the electronic structure and the Fermi surfaces.