Search results for "Clusters"
showing 10 items of 1274 documents
Site Preference in Multimetallic Nanoclusters: Incorporation of Alkali Metal Ions or Copper Atoms into the Alkynyl-Protected Body-Centered Cubic Clus…
2016
The synthesis, structure, substitution chemistry, and optical properties of the gold-centered cubic monocationic cluster [Au@Ag8@Au6(C≡CtBu)12]+ are reported. The metal framework of this cluster can be described as a fragment of a body-centered cubic (bcc) lattice with the silver and gold atoms occupying the vertices and the body center of the cube, respectively. The incorporation of alkali metal atoms gave rise to [MnAg8−nAu7(C≡CtBu)12]+ clusters (n=1 for M=Na, K, Rb, Cs and n=2 for M=K, Rb), with the alkali metal ion(s) presumably occupying the vertex site(s), whereas the incorporation of copper atoms produced [CunAg8Au7−n(C≡CtBu)12]+ clusters (n=1–6), with the Cu atom(s) presumably occup…
Crystal structure ofp-toluenesulfonylmethyl isocyanide
2015
The molecule of the commercially available title compound, C9H9NO2S, has crystallographically imposed mirror symmetry, the mirror plane passing through the isocyanide group and thepara-C atoms, the methyl C atom and the S atom of the methyl 4-tolyl sulfone moiety. In the crystal, C—H...O hydrogen-bond interactions link the molecules into chains running parallel to thebaxis.
The dynamics of magnetic ordering in a natural hemo-ilmenite solid solution
2007
Geophysical Journal International, 169 (3)
Toward a density functional description of liquid pH2.
2010
A finite-temperature density functional approach to describe the properties of parahydrogen in the liquid-vapor coexistence region is presented. The first proposed functional is zero-range, where the density-gradient term is adjusted so as to reproduce the surface tension of the liquid-vapor interface at low temperature. The second functional is finite-range and, while it is fitted to reproduce bulk pH2 properties only, it is shown to yield surface properties in good agreement with experiments. These functionals are used to study the surface thickness of the liquid-vapor interface, the wetting transition of parahydrogen on a planar Rb model surface, and homogeneous cavitation in bulk liquid…
Water interaction with perfect and fluorine-doped Co3O4 (100) surface
2015
Abstract We report the results of theoretical investigations of water adsorption on undoped and fluorine-doped Co3O4 (100) surface by means of the plane-wave periodic density functional theory (DFT) calculations combined with the Hubbard-U approach and statistical thermodynamics. We discuss the effect of fluorine-doping of the Co3O4 (100) surface and calculated oxygen evolution reaction overpotential based on the Gibbs free-energy diagram of undoped and F-doped surfaces.
Quenched molecular dynamics studies on the extraction energy of aluminum atoms
2007
The extraction energy of an aluminum atom is calculated at 0 K as a function of coordination number and defect depth for three surface orientations [(100), (110) and (111)]. For each orientation, atoms are selected and extracted one by one. A linear relationship is obtained between the extraction energy of surface atoms and their coordination numbers (with slight variations due to the geometrical configuration of the atoms). However, the study of the influence of the defect depth on the extraction energy highlights the role played by intrinsic stress on the extraction energy. Copyright © 2008 John Wiley & Sons, Ltd.
Adsorption of organic compounds at the surface of Enceladus' ice grains. A grand canonical Monte Carlo simulation study
2021
International audience; In this paper, we characterise the adsorption of ethylene, propanol and hexanal molecules on crystalline ice by grand canonical Monte Carlo simulations performed at 236 K, a temperature which is typical of some Enceladus’ environments. We show that at low coverage of the ice surface, the adsorption of propanol and hexanal is driven by the interaction of these molecules with the ice phase and, as a consequence, the adsorbed molecules lie more or less parallel to the ice surface. On the other hand, upon saturation, the adsorbate–adsorbate interactions become more and more important and the molecules tend to become tilted with respect to the surface, the aliphatic chain…
Growth, domain structure, and atomic adsorption sites of hBN on the Ni(111) surface
2021
One of the most important functionalities of the atomically thin insulator hexagonal boron nitride (hBN) is its ability to chemically and electronically decouple functional materials from highly reactive surfaces. It is therefore of utmost importance to uncover its structural properties on surfaces on an atomic and mesoscopic length scale. In this paper, we quantify the relative coverages of structurally different domains of a hBN layer on the Ni(111) surface using low-energy electron microscopy and the normal incidence x-ray standing wave technique. We find that hBN nucleates on defect sites of the Ni(111) surface and predominantly grows in two epitaxial domains that are rotated by ${60}^{…
Metal clusters on an inert surface: A simple model
1997
The shapes of metal clusters (with 2 to 14 valence electrons) on an inert surface are studied with a simple model based on the ultimate jellium model. It is shown that within certain approximations the surface-cluster interaction can be described with an external potential in the Kohn-Sham method. No restrictions for the cluster geometry are imposed. The results show that depending on the strength of the interaction and on the size of the cluster, the ground state is either planar or three-dimensional, but in many cases both geometries are stable and there is a marked energy barrier between them. The results agree qualitatively with ab initio calculations of Na clusters on a NaCl(100) surfa…
Noble-gas bubbles in metals: Molecular-dynamics simulations and positron states.
1987
A theoretical treatment of atomic structure and positron states in noble-gas bubbles in metals is presented. The Al-He and Cu-Kr systems are considered as specific examples. For large bubbles (radii above a few tens of angstroms) a calculational scheme is developed combining molecular-dynamics results for the metal--noble-gas interface with positron calculations. It is demonstrated that a positron is trapped at the surface of a noble-gas bubble, i.e., at the metal-gas interface. The annihilation rate with metal electrons is similar to that at a clean surface, while simultaneously there is a significant annihilation rate with gas-atom electrons. This enables relationships between the gas den…