Density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations were performed to represent carbon dots surfaces. The addition of different oxygen functional groups to the aromatic carbon core structure and the stability in the interaction with silver nanoparticles was also investigated. Adsorption energies were evaluated in order to compare the competition for adsorption sites on silver surface with D-glucose and D-gluconate ion molecules. The -COOH and -COO groups and the interaction of the latter with silver were proposed to explain some features of the UV-visible absorption spectra, which could also contribute to an explanation for the charge observed on carbon dot surfaces.
Theoretical studies on the total energy, electronic structure, and bonding of the Zr 0.9 Ti 0.1 NiMn 0.5 Cr 0.25 V 0.25 alloy and its hydrides were performed using density functional theory calculations. This alloy crystallizes in the C14 Laves phase. To determine the equilibrium structural parameters for this compound, we performed lattice constants optimization. The optimized c/a ratio was found in good agreement with experimental data. When hydrogen is introduced in the AB 2 matrix, there are different sites to localize it with a variety of local environments. We found that A 2 B 2 sites are preferentially occupied. After hydrogenation, the volume of the alloy increases, whereas the binding energy remains practically the same up to 3.5 H/FU, indicating little interaction among hydrogen atoms. The electronic structure of AB 2 and AB 2 H 3.5 phases is also analyzed.
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