Zn-doping and oxygen vacancy effects on the reactivity and properties of monoclinic and tetragonal ZrO: a DFT study.

Zirconia oxide (ZrO) is a material that has aroused great interest in the scientific community for its general use in various technological applications, such as fuel cells, solar cells, electronic devices, catalysis, dental biomaterial and ceramics. When it is applied as a catalyst, the doping and vacancy effects of their crystalline phases are important properties to guide new developments. This work investigates tetragonal and monoclinic crystalline phases of the Zn-doped ZrO by periodic density functional calculations.

Bulk and surface theoretical investigation of Nb-doped δ-FeOOH as a promising bifunctional catalyst.

The development of bifunctional catalysts is of great interest in fine chemistry, since they are capable of promoting multicatalytic reactions involved in several important industrial processes. Iron oxyhydroxides have been identified as low-cost bifunctional catalysts. However, their applications are limited due to their weak acid character.

DFT calculations for structural prediction and applications of intercalated lamellar compounds.

The intercalated layered materials are commonly built from structures complex enough to have large unit cells and, because of this, calculations of their electronic structures are very demanding in terms of memory, processing and time. Also, the versatility of these compounds enables the synthesis of a large number of derived materials difficult to characterize. Only in the last two decades, a combination of theoretical methodologies and advances in processing made density-functional theory (DFT) calculations quite interesting as an investigation tool for this family of materials.

Combining Nuclear Magnetic Resonance Spectroscopy and Density Functional Theory Calculations to Characterize Carvedilol Polymorphs.

The experiments of carvedilol form II, form III, and hydrate by (13)C and (15)N cross-polarization magic-angle spinning (CP MAS) are reported. The GIPAW (gauge-including projector-augmented wave) method from DFT (density functional theory) calculations was used to simulate (13)C and (15)N chemical shifts. A very good agreement was found for the comparison between the global results of experimental and calculated nuclear magnetic resonance (NMR) chemical shifts for carvedilol polymorphs.

Theoretical study of the reaction between HF molecules and hydroxyl layers of Mg(OH)2.

The reaction of HF molecules with brucite, Mg(OH)(2), leading to the formation of Mg(OH)(2-x)F(x), was theoretically studied by ab initio density functional theory (DFT) with periodic boundary conditions. We proposed as mechanism for this reaction four elementary steps: adsorption of the HF molecule, OH(-) liberation from brucite as a water molecule, desorption of the newly formed H(2)O, and rearrangement of the F(-) anion into a hydroxyl position. For the Mg(OH)(2-x)F(x) formation, with x = 1/9, the final product, outcome from an initially adsorbed HF molecule, we computed the Helmholtz free energy variation DeltaF = -23 kcal/mol.