Norberto Castellani | Universidad Nacional del Sur (original) (raw)

Papers by Norberto Castellani

Research paper thumbnail of Theoretical studies of CO adsorption and dissociation on Ru in presence of Cl or MoO x

Catalysis Letters, 1993

Using the extended Hückel molecular orbital method we studied the adsorption and dissociation of ... more Using the extended Hückel molecular orbital method we studied the adsorption and dissociation of CO over a Ru cluster with Cl or MoO preadsorbed onto it. Previous experimental information oriented us to think that the remaining Cl present in Ru/SiO2 and RuMo/SiO2 catalysts could influence their chemisorptive and catalytic properties. On this basis our theoretical model explains the observed activity

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Research paper thumbnail of On the difficulties of present theoretical models to predict the oxidation state of atomic Au adsorbed on regular sites of CeO (111)

The electronic structure and oxidation state of atomic Au adsorbed on a perfect surface have been... more The electronic structure and oxidation state of atomic Au adsorbed on a perfect surface have been investigated in detail by means of periodic density functional theory-based calculations, using the and potentials for a broad range of values, complemented with calculations employing the HSE06 hybrid functional. In addition, the effects of the lattice parameter and of the starting point for the geometry optimization have also been analyzed.

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Research paper thumbnail of Relation between the intensity of Auger lines and the cross-relaxation energy in oxygen KLL lines of oxides

Surface and Interface Analysis, 1992

A calculation method is described and used to obtain the net ionic oxygen extra-charge in oxides ... more A calculation method is described and used to obtain the net ionic oxygen extra-charge in oxides from the O KLL Auger intensities. The relation with the O KLL cross-relaxation energies is also discussed.

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Research paper thumbnail of Core-electron relaxation energy in small metallic particles

Chemical Physics, 1985

ABSTRACT

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Research paper thumbnail of Theoretical study of hydrogen adsorption on FePd face-centered cubic alloy surfaces

Physical Review B, 2005

... of hydrogen adsorption on FePd face-centered cubic alloy surfaces Paula V. Jasen, Estela A. G... more ... of hydrogen adsorption on FePd face-centered cubic alloy surfaces Paula V. Jasen, Estela A. Gonzalez, Norberto J. Castellani ... On the other hand, Dominguez et al. ... The k-points set were generated according to the geometrical method of Ramirez and B?48,49 The adsorption on ...

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Research paper thumbnail of The effect of interstitial hydrogen on the electronic structure of Fe–Pd alloys

Journal of Physics and Chemistry of Solids, 2004

The electronic structure and bonding in Fe–Pd alloys were computed using a tight binding method. ... more The electronic structure and bonding in Fe–Pd alloys were computed using a tight binding method. Two phases have been identified for these alloys, a high temperature fcc and a low temperature fct structure. The hydrogen absorption turns out to be a favorable process in both structures. The hydrogen at tetrahedral interstitial site for the fct structure is 2.2eV more stable

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Research paper thumbnail of Ethanol adsorption on MgO surface with and without defects from a theoretical point of view

Surface Science, 2009

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Research paper thumbnail of DFT studies of zirconocene/MAO interaction

Journal of Molecular Catalysis A-chemical, 2003

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Research paper thumbnail of CO interaction with Au atoms adsorbed on terrace, edge and corner sites of the MgO(1 0 0) surface. Electronic structure and vibrational analysis from DFT

Surface Science, 2009

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Research paper thumbnail of Methanol decomposition on the β-Ga 2O 3 (1 0 0) surface: A DFT approach

Applied Surface Science, 2007

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Research paper thumbnail of Interaction of NO with Au nanoparticles supported on (100) terraces and topological defects of MgO

Surface Science, 2011

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Research paper thumbnail of Interaction of NO with Au nanoparticles supported on (100) terraces and topological defects of MgO

Surface Science, 2011

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Research paper thumbnail of Unusual coordination in a silver thionate complex. Synthesis, structural characterization and theoretical calculations of dinuclear and polynuclear silver(I) thiosaccharinates with pyridine and 1,10-phenanthroline

Polyhedron, 2008

ABSTRACT Treatment of Ag6(tsac)6 (tsac=thiosaccharinate anion) with pyridine (py) and 1,10-phenan... more ABSTRACT Treatment of Ag6(tsac)6 (tsac=thiosaccharinate anion) with pyridine (py) and 1,10-phenanthroline (o-phen) each affords two novel silver(I)-thiosaccharinate complexes: dinuclear [Ag2(tsac)2py] (1) and polynuclear [Ag(tsac)(o-phen)]n (2). Both crystal structures have been determined by X-ray diffraction and spectroscopic structural analysis (IR and Raman, UV–Vis, 1H and 13C NMR) have also been made for both compounds. Thermal stability analysis (TGA and DTA) of complex 1 are used to confirm the strength of the pyridine coordination to the silver ion. The molecular structure of complex 1 shows some astonishing characteristics. The two silver atoms are in different environments: one of them is surrounded by two S atoms, while the other completes its coordination sphere by three N atoms, two from the thiosaccharinate anions and the third from a pyridine molecule. The short Ag(1)–Ag(2) contact distance, 2.9681(8)Å, indicates an interaction between the two silver metal atoms exists. Complex 2 shows a thiosaccharinate molecule bridging two silver atoms through the exocyclic S atom while the o-phenanthroline ligand is coordinated as a bidentate N,N chelate, forming a polynuclear chain. Quantum chemical calculations confirm the argentophilic character of the Ag–Ag interaction in complex 1, and its structure and vibrational assignments were correlated and confirmed theoretically.

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Research paper thumbnail of On the difficulties of present theoretical models to predict the oxidation state of atomic Au adsorbed on regular sites of CeO2(111

Chemical Physics, 2009

The electronic structure and oxidation state of atomic Au adsorbed on a perfect CeO2(111) surface... more The electronic structure and oxidation state of atomic Au adsorbed on a perfect CeO2(111) surface have been investigated in detail by means of periodic density functional theory-based calculations, using the LDA+U and GGA+U potentials for a broad range of U values, complemented with calculations employing the HSE06 hybrid functional. In addition, the effects of the lattice parameter a0 and of the starting point for the geometry optimization have also been analyzed. From the present results we suggest that the oxidation state of single Au atoms on CeO2(111) predicted by LDA+U, GGA+U, and HSE06 density functional calculations is not conclusive and that the final picture strongly depends on the method chosen and on the construction of the surface model. In some cases we have been able to locate two well-defined states which are close in energy but with very different electronic structure and local geometries, one with Au fully oxidized and one with neutral Au. The energy difference between the two states is typically within the limits of the accuracy of the present exchange-correlation potentials, and therefore, a clear lowest-energy state cannot be identified. These results suggest the possibility of a dynamic distribution of Au0 and Au+ atomic species at the regular sites of the CeO2(111) surface.

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Research paper thumbnail of Hydrogen molecule dissociation on Pt Ni(111) systems

Surface Science, 1996

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Research paper thumbnail of NCO adsorption over SiO 2 and Cu/SiO 2 cluster models from density functional theory

Journal of Molecular Catalysis A-chemical, 2004

The adsorption of NCO over two types of surface defects on silica surface, Si and SiO, were studi... more The adsorption of NCO over two types of surface defects on silica surface, Si and SiO, were studied using the density functional theory formalism. The adsorption is preferred on Si site in agreement with experimental results. The NCO adsorption is also studied over atomic and dimer copper deposited on silica defects and, for comparison reasons, on free Cu and Cu2.

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Research paper thumbnail of Methanol adsorption on magnesium oxide surface with defects: a DFT study

Surface Science, 2003

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Research paper thumbnail of Adhesion and bonding of Pt/Ni and Pt/Co overlayers: Density functional calculations

Journal of Physics and Chemistry of Solids, 2006

... Hammer and Nørskov [15] and [16] showed that the heat of adsorption of gases on transition me... more ... Hammer and Nørskov [15] and [16] showed that the heat of adsorption of gases on transition metals (TM) should linearly increase as the energy of the center of the d-band increases, while the heat of adsorption decreases linearly with the strength of the Pauli repulsions. ...

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Research paper thumbnail of The adsorption of 1,3-butadiene on Pd/Ni multilayers: The interplay between spin polarization and chemisorption strength

Journal of Solid State Chemistry, 2010

... Guillermina G mez, Patricia G. Belelli a,* , Gabriela F. Cabeza a , Norberto J. Castellani a ... more ... Guillermina G mez, Patricia G. Belelli a,* , Gabriela F. Cabeza a , Norberto J. Castellani a Grupo de Materiales y Sistemas Catal ticos, Departamento de F sica, Universidad Nacional del Sur, Av. ... [17] L. Piccolo, A. Valcarcel, M. Bausach, C. Thomazeau, D. Uzio, G. Berhault, Phys. ...

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Research paper thumbnail of Formation of Ag 2, Au 2 and AgAu particles on MgO(1 0 0): DFT study on the role of support-induced charge transfer in metal–metal interactions

Applied Surface Science, 2009

The formation of Ag2, Au2 and AgAu particles oriented perpendicularly to the MgO(100) surface was... more The formation of Ag2, Au2 and AgAu particles oriented perpendicularly to the MgO(100) surface was studied using the density functional theory. While the support induces a slight enhancement of the Ag–Ag bond (by 0.3–0.4eV), the Au–Au bond is strongly enhanced (by 0.8–1.1eV). Concerning the bimetallic particle, the Ag–Au bond stabilization depends on the relative position of each atom. Thus, in general terms, the strength of the metal–metal bond is determined by the nature of the terminal atom; the bond is stronger in Au-terminal particles. The partial electronic charge transfer to the terminal Au atom and its ability to polarize this charge are responsible for this energetic stabilization.

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Research paper thumbnail of Theoretical studies of CO adsorption and dissociation on Ru in presence of Cl or MoO x

Catalysis Letters, 1993

Using the extended Hückel molecular orbital method we studied the adsorption and dissociation of ... more Using the extended Hückel molecular orbital method we studied the adsorption and dissociation of CO over a Ru cluster with Cl or MoO preadsorbed onto it. Previous experimental information oriented us to think that the remaining Cl present in Ru/SiO2 and RuMo/SiO2 catalysts could influence their chemisorptive and catalytic properties. On this basis our theoretical model explains the observed activity

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Research paper thumbnail of On the difficulties of present theoretical models to predict the oxidation state of atomic Au adsorbed on regular sites of CeO (111)

The electronic structure and oxidation state of atomic Au adsorbed on a perfect surface have been... more The electronic structure and oxidation state of atomic Au adsorbed on a perfect surface have been investigated in detail by means of periodic density functional theory-based calculations, using the and potentials for a broad range of values, complemented with calculations employing the HSE06 hybrid functional. In addition, the effects of the lattice parameter and of the starting point for the geometry optimization have also been analyzed.

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Research paper thumbnail of Relation between the intensity of Auger lines and the cross-relaxation energy in oxygen KLL lines of oxides

Surface and Interface Analysis, 1992

A calculation method is described and used to obtain the net ionic oxygen extra-charge in oxides ... more A calculation method is described and used to obtain the net ionic oxygen extra-charge in oxides from the O KLL Auger intensities. The relation with the O KLL cross-relaxation energies is also discussed.

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Research paper thumbnail of Core-electron relaxation energy in small metallic particles

Chemical Physics, 1985

ABSTRACT

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Research paper thumbnail of Theoretical study of hydrogen adsorption on FePd face-centered cubic alloy surfaces

Physical Review B, 2005

... of hydrogen adsorption on FePd face-centered cubic alloy surfaces Paula V. Jasen, Estela A. G... more ... of hydrogen adsorption on FePd face-centered cubic alloy surfaces Paula V. Jasen, Estela A. Gonzalez, Norberto J. Castellani ... On the other hand, Dominguez et al. ... The k-points set were generated according to the geometrical method of Ramirez and B?48,49 The adsorption on ...

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Research paper thumbnail of The effect of interstitial hydrogen on the electronic structure of Fe–Pd alloys

Journal of Physics and Chemistry of Solids, 2004

The electronic structure and bonding in Fe–Pd alloys were computed using a tight binding method. ... more The electronic structure and bonding in Fe–Pd alloys were computed using a tight binding method. Two phases have been identified for these alloys, a high temperature fcc and a low temperature fct structure. The hydrogen absorption turns out to be a favorable process in both structures. The hydrogen at tetrahedral interstitial site for the fct structure is 2.2eV more stable

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Research paper thumbnail of Ethanol adsorption on MgO surface with and without defects from a theoretical point of view

Surface Science, 2009

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Research paper thumbnail of DFT studies of zirconocene/MAO interaction

Journal of Molecular Catalysis A-chemical, 2003

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Research paper thumbnail of CO interaction with Au atoms adsorbed on terrace, edge and corner sites of the MgO(1 0 0) surface. Electronic structure and vibrational analysis from DFT

Surface Science, 2009

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Research paper thumbnail of Methanol decomposition on the β-Ga 2O 3 (1 0 0) surface: A DFT approach

Applied Surface Science, 2007

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Research paper thumbnail of Interaction of NO with Au nanoparticles supported on (100) terraces and topological defects of MgO

Surface Science, 2011

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Research paper thumbnail of Interaction of NO with Au nanoparticles supported on (100) terraces and topological defects of MgO

Surface Science, 2011

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Research paper thumbnail of Unusual coordination in a silver thionate complex. Synthesis, structural characterization and theoretical calculations of dinuclear and polynuclear silver(I) thiosaccharinates with pyridine and 1,10-phenanthroline

Polyhedron, 2008

ABSTRACT Treatment of Ag6(tsac)6 (tsac=thiosaccharinate anion) with pyridine (py) and 1,10-phenan... more ABSTRACT Treatment of Ag6(tsac)6 (tsac=thiosaccharinate anion) with pyridine (py) and 1,10-phenanthroline (o-phen) each affords two novel silver(I)-thiosaccharinate complexes: dinuclear [Ag2(tsac)2py] (1) and polynuclear [Ag(tsac)(o-phen)]n (2). Both crystal structures have been determined by X-ray diffraction and spectroscopic structural analysis (IR and Raman, UV–Vis, 1H and 13C NMR) have also been made for both compounds. Thermal stability analysis (TGA and DTA) of complex 1 are used to confirm the strength of the pyridine coordination to the silver ion. The molecular structure of complex 1 shows some astonishing characteristics. The two silver atoms are in different environments: one of them is surrounded by two S atoms, while the other completes its coordination sphere by three N atoms, two from the thiosaccharinate anions and the third from a pyridine molecule. The short Ag(1)–Ag(2) contact distance, 2.9681(8)Å, indicates an interaction between the two silver metal atoms exists. Complex 2 shows a thiosaccharinate molecule bridging two silver atoms through the exocyclic S atom while the o-phenanthroline ligand is coordinated as a bidentate N,N chelate, forming a polynuclear chain. Quantum chemical calculations confirm the argentophilic character of the Ag–Ag interaction in complex 1, and its structure and vibrational assignments were correlated and confirmed theoretically.

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Research paper thumbnail of On the difficulties of present theoretical models to predict the oxidation state of atomic Au adsorbed on regular sites of CeO2(111

Chemical Physics, 2009

The electronic structure and oxidation state of atomic Au adsorbed on a perfect CeO2(111) surface... more The electronic structure and oxidation state of atomic Au adsorbed on a perfect CeO2(111) surface have been investigated in detail by means of periodic density functional theory-based calculations, using the LDA+U and GGA+U potentials for a broad range of U values, complemented with calculations employing the HSE06 hybrid functional. In addition, the effects of the lattice parameter a0 and of the starting point for the geometry optimization have also been analyzed. From the present results we suggest that the oxidation state of single Au atoms on CeO2(111) predicted by LDA+U, GGA+U, and HSE06 density functional calculations is not conclusive and that the final picture strongly depends on the method chosen and on the construction of the surface model. In some cases we have been able to locate two well-defined states which are close in energy but with very different electronic structure and local geometries, one with Au fully oxidized and one with neutral Au. The energy difference between the two states is typically within the limits of the accuracy of the present exchange-correlation potentials, and therefore, a clear lowest-energy state cannot be identified. These results suggest the possibility of a dynamic distribution of Au0 and Au+ atomic species at the regular sites of the CeO2(111) surface.

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Research paper thumbnail of Hydrogen molecule dissociation on Pt Ni(111) systems

Surface Science, 1996

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Research paper thumbnail of NCO adsorption over SiO 2 and Cu/SiO 2 cluster models from density functional theory

Journal of Molecular Catalysis A-chemical, 2004

The adsorption of NCO over two types of surface defects on silica surface, Si and SiO, were studi... more The adsorption of NCO over two types of surface defects on silica surface, Si and SiO, were studied using the density functional theory formalism. The adsorption is preferred on Si site in agreement with experimental results. The NCO adsorption is also studied over atomic and dimer copper deposited on silica defects and, for comparison reasons, on free Cu and Cu2.

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Research paper thumbnail of Methanol adsorption on magnesium oxide surface with defects: a DFT study

Surface Science, 2003

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Research paper thumbnail of Adhesion and bonding of Pt/Ni and Pt/Co overlayers: Density functional calculations

Journal of Physics and Chemistry of Solids, 2006

... Hammer and Nørskov [15] and [16] showed that the heat of adsorption of gases on transition me... more ... Hammer and Nørskov [15] and [16] showed that the heat of adsorption of gases on transition metals (TM) should linearly increase as the energy of the center of the d-band increases, while the heat of adsorption decreases linearly with the strength of the Pauli repulsions. ...

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Research paper thumbnail of The adsorption of 1,3-butadiene on Pd/Ni multilayers: The interplay between spin polarization and chemisorption strength

Journal of Solid State Chemistry, 2010

... Guillermina G mez, Patricia G. Belelli a,* , Gabriela F. Cabeza a , Norberto J. Castellani a ... more ... Guillermina G mez, Patricia G. Belelli a,* , Gabriela F. Cabeza a , Norberto J. Castellani a Grupo de Materiales y Sistemas Catal ticos, Departamento de F sica, Universidad Nacional del Sur, Av. ... [17] L. Piccolo, A. Valcarcel, M. Bausach, C. Thomazeau, D. Uzio, G. Berhault, Phys. ...

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Research paper thumbnail of Formation of Ag 2, Au 2 and AgAu particles on MgO(1 0 0): DFT study on the role of support-induced charge transfer in metal–metal interactions

Applied Surface Science, 2009

The formation of Ag2, Au2 and AgAu particles oriented perpendicularly to the MgO(100) surface was... more The formation of Ag2, Au2 and AgAu particles oriented perpendicularly to the MgO(100) surface was studied using the density functional theory. While the support induces a slight enhancement of the Ag–Ag bond (by 0.3–0.4eV), the Au–Au bond is strongly enhanced (by 0.8–1.1eV). Concerning the bimetallic particle, the Ag–Au bond stabilization depends on the relative position of each atom. Thus, in general terms, the strength of the metal–metal bond is determined by the nature of the terminal atom; the bond is stronger in Au-terminal particles. The partial electronic charge transfer to the terminal Au atom and its ability to polarize this charge are responsible for this energetic stabilization.

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