J. Ulises Reveles

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Dopamine forms an initial structure coordinated to the surface of the iron oxide nanoparticle as a result of improved orbital overlap of the five-membered ring and a reduced steric environment of the iron complex. However, through transfer of electrons to the iron cations on the surface and rearrangement of the oxidized dopamine, a semiquinone is formed.(More)
First principles electronic structure calculations have been carried out to investigate the ground state geometry, electronic structure, and the binding energy of [Au(H2O)n]+ clusters containing up to 10 H2O molecules. It is shown that the first coordination shell of Au+ contains two H2O molecules forming a H2O-Au+-H2O structure with C2 symmetry. Subsequent(More)
An experimental and theoretical study of bismuth-doped aluminum clusters in the gas phase has revealed two particularly stable clusters, namely, Al(3)Bi and Al(5)Bi. We show that their electronic structure can be understood in terms of the aromatic and "Jellium" models, respectively. Negative ion photodetachment spectra provide a fingerprint of the(More)
The quantum states in metal clusters are grouped into bunches of close-lying eigenvalues, termed electronic shells, similar to those of atoms. Filling of the electronic shells with paired electrons results in local minima in energy to give stable species called magic clusters. This led to the realization that selected clusters mimic chemical properties of(More)
We recently demonstrated that, in gas phase clusters containing aluminum and iodine atoms, an Al(13) cluster behaves like a halogen atom, whereas an Al(14) cluster exhibits properties analogous to an alkaline earth atom. These observations, together with our findings that Al(13)(-) is inert like a rare gas atom, have reinforced the idea that chosen clusters(More)
It is shown that the magnetic moments of Sc atoms can be significantly enhanced by combining them with alkali atoms. We present results of first principles electronic structure calculations of ScNa(n) (1 < or = n < or = 12) clusters that indicate that a ScNa(12) cluster consisting of a Sc atom surrounded by 12 Na atoms forming a compact icosahedral(More)
The quantum states in metal clusters bunch into supershells with associated orbitals having shapes resembling those in atoms, giving rise to the concept that selected clusters could mimic the characteristics of atoms and be classified as superatoms. Unlike atoms, the superatom orbitals span over multiple atoms and the filling of orbitals does not usually(More)
An adaptive numerical integrator for the exchange-correlation energy and potential is presented. It uses the diagonal elements of the exchange-correlation potential matrix as a grid generating function. The only input parameter is the requested grid tolerance. In combination with a defined cell function the adaptive grid generation scales almost linear with(More)
The use of Hermite Gaussian auxiliary function densities from the variational fitting of the Coulomb potential for the calculation of exchange-correlation potentials is discussed. The basic working equations for the energy and gradient calculation are derived. The accuracy of this approximation for optimized structure parameters and bond energies are(More)
The geometry optimization in delocalized internal coordinates is discussed within the framework of the density functional theory program deMon. A new algorithm for the selection of primitive coordinates according to their contribution to the nonredundant coordinate space is presented. With this new selection algorithm the excessive increase in computational(More)