Narrow Results

We present a combined computational/experimental study of fluorescent Au nanocluster complexes synthesized using small biological molecules. Using density-functional theory, we calculated the binding energy, HOMO–LUMO gap, charge transfer, and bond length of the ligand–Au nanocluster systems. These calculations suggest the formation of ligand–Au nanocluster complexes. We further simulated the HOMO/LUMO states and the absorption spectra of the complexes. The HOMO and LUMO states of the complexes were confined within the Au nanoclusters, suggesting little ligand intrinsic fluorescence. The simulated absorption spectra agreed reasonably well with the experimental data. The simulation results of different systems demonstrate the strong ligand effects on the fluorescent emissions of ligand–Au nanocluster complexes. Our studies provide valuable information for the rational design of next-generation fluorescent tags.

We adapt the classical Ornstein-Zernike equation for the direct correlation function of classical theory of liquids in order to obtain a model for the exchange-correlation hole based on the electronic direct correlation function. Because we explicitly account for the identical-particle nature of electrons, our result recovers the normalization of the exchange-correlation hole. In addition, the modified direct correlation function is shorted-ranged compared to the classical formula. Functionals based on hole models require six-dimensional integration of a singular integrand to evaluate the exchange-correlation energy, and we present several strategies for efficiently evaluating the exchange-correlation integral in a numerically stable way.

The study of bimetallic catalysts has scientific and technologic importance because of special catalytic activity towards several reactions. RhCu is an interesting bimetallic system due to combination of the very different catalytic activities of Rh and Cu. The catalytic activity of this bimetallic does not result from simple interpolation of the constituents. In fact, at low Cu content, the catalytic activity of RhCu is superior to that of Rh but when the Cu content is higher the activity decays. This is a curious trend which theoretical works had attempted to explain. This paper reports an overview of the most recent research works about this bimetallic system with emphasis in its especial characteristics.