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CO2 is the most abundant greenhouse gas, and for this reason, it is the main target for finding solutions to climatic change. A strategy of environmental remediation is the transformation of CO2 to an aggregated value product to generate a carbon-neutral cycle. CO2 reduction is a great challenge because of the large C=O dissociation energy, ~179 kcal/mol. Heterogeneous photocatalysis is a strategy to address this issue, where the adsorption process is the fundamental step. The focus of this work is the role of adsorption in CO2 reduction by means of modeling the CO2 adsorption in rutile metallic oxides (TiO2, GeO2, SnO2, IrO2 and PbO2) using Density Functional Theory (DFT) and periodic DFT methods. The comparison of adsorption on different metal oxides forming the same type of crystal structure allowed us to observe the influence of the metal in the adsorption process. In the same way, we performed a comparison of the adsorption capability between two different surface planes, (001) and (110). Two CO2 configurations were observed, linear and folded: the folded conformations were observed in TiO2, GeO2 and SnO2, while the linear conformations were present in IrO2 and PbO2. The largest adsorption efficiency was displayed by the (001) surface planes. The CO2 linear and folded configurations were related to the interaction of the oxygen on the metallic surface with the adsorbate carbon, and the linear conformations were associated with the physisorption and folded configurations with chemisorption. TiO2 was the material with the best performance for CO2 interactions during the adsorption. [ABSTRACT FROM AUTHOR]

The reaction mechanism of the tricarbonylchromium complex haptotropic rearrangement between six-membered rings arranged like in naphthalene of four polycyclic aromatic hydrocarbons (PAHs) is examined. Results suggest that the curvature of the organic substrate is responsible for slowing down the rearrangement.

Research has been conducted on Cu (sub)2 (mu-Cl) (sub)2 Cl (sub)2 (L) (sub)2] (L= dialkylpyridine-2,6-dicarboxylate) complexes. The preparation of these complexes, their crystal structure and magnetic properties have been investigated, and the details are reported.

Research has been conducted on the II-VI semiconductor nanoparticles including cadmium chalcogen. The use of the chalcogen sites of the nanoparticle surface in investigating the nanoparticle surface interaction with organic chromophore p-orbitals is described.

Issues concerning the electronic processes during the surface modification of nanoparticles are discussed.

Research into potential liquid-state nuclear magnetic resonance spectroscopy for elucidating the structure of the nanoparticles (NP) surface and to find a synthesis of NP with surface properties for competitive modification is analysed.

We report a theoretical study of how the physical and chemical properties of the Ga12As12 cluster change upon doping with atomic impurities of groups p and d. Calculations were performed within the density functional theory with the generalized gradient approximation to the exchange and correlation energy functional. We consider the Ga11As12X and Ga12As11X doped clusters, where X is an atomic impurity (from B-P, Al-Cl, Cr-Cu and Mo-Ag in their respective series) that substitutes either a Ga or an As atom at. We found that, in general, the substitution of a Ga atom is a more exothermic process than the substitution of an As one, in accordance with experimental reports on doped GaAs bulk. Some of the transition metal dopants (Cr, Mn, Fe, Mo and Tc) interact in such a way that the magnetic moment of the clusters is enhanced. We discuss the doping effect by analyzing the structural changes, binding energies per atom, HOMO–LUMO gaps, and relevant vertical chemical descriptors. [ABSTRACT FROM AUTHOR]

Research has been conducted on dinuclear copper(I) complexes with hexaaza macrocyclic ligand. The authors describe the synthesis and spectroscopic characterization of these complexes.

The concept of local pressure in an electronic system is extended and developed, starting from an integral relation of Bartolotti and Parr (Ref. 11) and using the local thermodynamic language of Ghosh, Berkowitz, and Parr (GBP) (Ref. 3), who have shown that for an ideal, noninteracting microscopic system the internal pressure at a point r is purely kinetic and given by ps=ρ(r)kT(r), where T(r) is an appropriately defined local temperature. In the present paper, we show that this equation, exact for the noninteracting, ideal system within the local thermodynamic transcription is a first order truncation of the real, interacting system pressure density functional, which contains explicit correlation and exchange pressure contributions, which act as ‘‘deviations from ideality’’ in the real system. From analogy with the macroscopic situation, the pressure density functional is written as a virial expansion in terms of the density. [ABSTRACT FROM AUTHOR]

The exchange energy density functional of an N electron atom is approximated by a combination of the Dirac and the Fermi–Amaldi approximations. The unknown coefficients of the combination are estimated by requiring that the sum of the Coulombic and exchange energies vanish when evaluated with the exact one-electron density. Evaluating the present functional with the Hartree–Fock densities of 1785 atoms and ions, and comparing the resulting exchange energies with the corresponding Hartree–Fock values gave an average error of 2%. The functional derivative has the correct long-range behavior, and leads to an Euler–Lagrange equation whose solutions gave energies which were in very good agreement with the Hartree–Fock values. [ABSTRACT FROM AUTHOR]