Quantum Chemistry on Parallel Computers: Concepts and Results of a Density Functional Method

Belling, Th.; Grauschopf, Th.; Krüger, Sven; Mayer, Markus; Nörtemann, Folke; Staufer, Markus; Zenger, Christoph; Rösch, Notker

doi:10.1007/978-3-642-60155-2_37

Cited by 53 publications

(52 citation statements)

References 6 publications

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“…30 All calculations were carried out with the linear combination of Gaussian-type orbitals fitting-functions density functional approach (LCGTO-FF-DF) to the Kohn-Sham problem 15 as implemented in the code PARAGAUSS (version 3.1.6). 40,41 Further computational details are provided as supplementary material. 42 Scalar relativistic effects were incorporated via the second-order Douglas-Kroll-Hess scheme.…”

Section: Computational Detailsmentioning

confidence: 99%

Scalable properties of metal clusters: A comparative study of modern exchange-correlation functionals

Koitz

Soini

Genest

et al. 2012

The Journal of Chemical Physics

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The performance of eight generalized gradient approximation exchange-correlation (xc) functionals is assessed by a series of scalar relativistic all-electron calculations on octahedral palladium model clusters Pd(n) with n = 13, 19, 38, 55, 79, 147 and the analogous clusters Au(n) (for n up through 79). For these model systems, we determined the cohesive energies and average bond lengths of the optimized octahedral structures. We extrapolate these values to the bulk limits and compare with the corresponding experimental values. While the well-established functionals BP, PBE, and PW91 are the most accurate at predicting energies, the more recent forms PBEsol, VMTsol, and VT{84}sol significantly improve the accuracy of geometries. The observed trends are largely similar for both Pd and Au. In the same spirit, we also studied the scalability of the ionization potentials and electron affinities of the Pd clusters, and extrapolated those quantities to estimates of the work function. Overall, the xc functionals can be classified into four distinct groups according to the accuracy of the computed parameters. These results allow a judicious selection of xc approximations for treating transition metal clusters.

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Section: Computational Detailsmentioning

confidence: 99%

Scalable properties of metal clusters: A comparative study of modern exchange-correlation functionals

Koitz

Soini

Genest

et al. 2012

The Journal of Chemical Physics

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“…[17,18] We employed the gradient-corrected exchangecorrelation functional BP86; [19,20] open-shell systems were described in spin-polarized fashion. In calculations involving 4d (Ag) and 5d atoms (Au), we used a scalar relativistic variant based on a second-order Douglas-Kroll transformation to decouple electronic and positronic degrees of freedom of the Dirac-Kohn-Sham equation.…”

Section: Computational Detailsmentioning

confidence: 99%

Density Functional Embedded Cluster Study of Cu₄, Ag₄ and Au₄ Species Interacting with Oxygen Vacancies on the MgO(001) Surface

Neyman

Inntam

Moskaleva

et al. 2006

Chemistry A European J

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Cu4, Ag4, and Au4 species adsorbed on an MgO(001) surface that exhibits neutral (Fs) and charged (Fs+) oxygen vacancies have been studied using a density functional approach and advanced embedding models. The gas‐phase rhombic‐planar structure of the coinage metal tetramers is only moderately affected by adsorption. In the most stable surface configuration, the plane of the tetramers is oriented perpendicular to the MgO(001) surface; one metal atom is attached to an oxygen vacancy and another one is bound to a nearby surface oxygen anion. A very similar structural motif was recently found on defect‐free MgO(001), where two O2− ions serve as adsorption sites. Following the trend of the interactions with the regular MgO(001) surface, Au4 and Cu4 bind substantially stronger to Fs and Fs+ sites than Ag4. This stronger adsorption interaction at oxygen vacancies, in particular at Fs, is partly due to a notable accumulation of electron density on the adsorbates. We also examined the propensity of small supported metal species to aggregate to adsorbed di‐, tri‐ and tetramers. Furthermore, we demonstrated that core‐level ionization potentials offer the possibility for detecting experimentally supported metal tetramers and characterizing them structurally with the help of calculated data.

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“…[7] The electronic-structure calculations were carried out with a density-functional method. [8][9][10][11][12][13] To evaluate the reaction energy for reverse hydrogen spillover from the OH groups of the zeolite to the supported Rh 6 cluster, we considered two systems: a) Rh 6 /Zeo(3H), in which the cluster is adsorbed on the model zeolite fragment with three bridging OH groups (Figure 1 a) corresponds to "nonreactive" adsorption of the Rh 6 cluster on the zeolite, and b) Rh 6 (3H)/Zeo, formed by reverse spillover from a), in which the hydrogen atoms are bound to the Rh 6 (Figure 1 b).…”

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Oxidation of Supported Rhodium Clusters by Support Hydroxy Groups

2003

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Metal clusters or particles on porous-oxide and zeolite supports are important industrial catalysts, with the role of the support often going beyond that of a mere platform for the stable dispersion of the metal. [1][2][3] The metal-support interaction involves support ligands, inferred to be surface oxygen or OH groups. How the bonding, reactivity, and catalytic properties of the metal depend on these ligands is essentially unresolved. Furthermore, supported metal catalysts often facilitate "spillover", whereby an adsorbate, typically H 2 , reacts with the metal to give species that migrate onto the support. Molecular hydrogen dissociates on metals, and some of the H 2 ultimately forms OH groups on the support. Spillover has been demonstrated, [4] but its chemistry is ill defined; it must involve redox processes, since H 2 is converted into a hydride bound to the metal and the protons in OH groups.To help clarify metal-support interactions and spillover effects, we modeled computationally the interaction of the bridging OH groups of zeolites with a supported cluster, Rh 6 , and compared the theoretical results with the experimental results. The model system was selected because of its close correspondence [5] to the EXAFS-derived structure parameters for zeolite-supported Rh 6 clusters.[6] Our calculations show that the interaction of the hexanuclear cluster with OH groups from the support leads to the oxidation of Rh atoms that are in close contact with the support; the energy released per OH group is estimated to be about 120 kJ molÀ1 . The results demonstrate the redox character of hydrogen spillover, which includes changes in the oxidation state of the supported metal.

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Quantum Chemistry on Parallel Computers: Concepts and Results of a Density Functional Method

Cited by 53 publications

References 6 publications

Scalable properties of metal clusters: A comparative study of modern exchange-correlation functionals

Scalable properties of metal clusters: A comparative study of modern exchange-correlation functionals

Density Functional Embedded Cluster Study of Cu₄, Ag₄ and Au₄ Species Interacting with Oxygen Vacancies on the MgO(001) Surface

Oxidation of Supported Rhodium Clusters by Support Hydroxy Groups

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Quantum Chemistry on Parallel Computers: Concepts and Results of a Density Functional Method

Cited by 53 publications

References 6 publications

Scalable properties of metal clusters: A comparative study of modern exchange-correlation functionals

Scalable properties of metal clusters: A comparative study of modern exchange-correlation functionals

Density Functional Embedded Cluster Study of Cu4, Ag4 and Au4 Species Interacting with Oxygen Vacancies on the MgO(001) Surface

Oxidation of Supported Rhodium Clusters by Support Hydroxy Groups

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Density Functional Embedded Cluster Study of Cu₄, Ag₄ and Au₄ Species Interacting with Oxygen Vacancies on the MgO(001) Surface