Search results for "Jellium"

showing 10 items of 28 documents

Magic triangular and tetrahedral clusters

1997

Using the methods of density functional theory and the jellium model we show that clusters with triangular [in two dimensions (2D)] or tetrahedral [in three dimensions (3D)] shapes have a strong shell structure and enhanced stability. Moreover, the shell closings correspond to the lowest magic numbers of a 2D and 3D harmonic oscillator and at the same time to the number of divalent atoms in close-packed triangles and tetrahedrons. Ab initio molecular dynamics simulations for Na and Mg clusters support the results of the jellium model.

Ab initio molecular dynamicsPhysicsJelliumPhysics::Atomic and Molecular ClustersMagic (programming)Shell (structure)TetrahedronDensity functional theoryAtomic physicsHarmonic oscillatorPhysical Review B
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Dipole surface plasmon in K+N clusters

1992

Abstract The technique of sum rules has been used to investigate the dipole surface plasmon for K + N clusters within a Density Functional Theory and the spherical jellium model. The role played by non-local effects is discussed comparing the results obtained from different functionals. Band-structure and core-polarization effects have been phenomenologically included in the calculation by means of an electron effective mass and a dielectric constant. Comparison with recent experimental data is presented.

Condensed matter physicsChemistryJelliumSurface plasmonGeneral ChemistryDielectricCondensed Matter PhysicsMolecular physicsSpherical modelDipoleEffective mass (solid-state physics)Materials ChemistryDensity functional theorySum rule in quantum mechanicsSolid State Communications
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Analysis of the Electronic Structure of Non-Spherical Ligand-Protected Metal Nanoclusters: The Case of a Box-Like Ag67

2016

In this work we introduce a new strategy to investigate the electronic shell structure of ligand-protected metal nanoclusters of polyhedral core shape. The central idea is to identify the symmetry of the Kohn–Sham molecular orbitals of an atomistic structure based on their projection onto the electronic states of a jellium system with a similar shape of the background charge density. Herein, we study the connection between a reduced atomistic model of the recently reported box-like [Ag67(SR)32(PR3)8]3+ nanocluster and a jellium box consisting of 32 free electrons. With this approach, we determine the symmetry of electronic states of the metal core and identify those that are involved in the…

Free electron modelJelliumnanoclusters02 engineering and technologyElectronic structureligand-protected metal nanoclusters010402 general chemistry01 natural sciencesMolecular physicsProjection (linear algebra)NanoclustersPhysics::Atomic and Molecular ClustersMolecular orbitalPhysical and Theoretical Chemistryta116Physicsta114electronic shell structures021001 nanoscience & nanotechnologySymmetry (physics)0104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsGeneral EnergyAtomic electron transitionAtomic physics0210 nano-technologyThe Journal of Physical Chemistry C
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Collision induced dissociation of stored gold cluster ions

1994

The stability of gold cluster ions Au + (2≦n≦23) has been investigated via collision induced dissociation in a Penning trap. Threshold energies and dissociation channels have been determined. The cluster stability exhibits a pronounced odd — even alternation: Clusters with an odd number of atoms,n, are more stable than the even-numbered ones. Enhanced stabilities are found for Au 3 + , Au 9 + , and Au 19 + in accordance with the Clemenger-Nilsson and the deformed jellium model of delocalized valence electrons. Excited odd cluster ions withn≦15 predominantly decay by evaporation of dimers; all others decay by monomer evaporation. From the dissociation channels estimates of the binding energi…

Gold clusterDelocalized electronMaterials scienceCollision-induced dissociationExcited stateJelliumPhysics::Atomic and Molecular ClustersAtomic physicsPenning trapAtomic and Molecular Physics and OpticsDissociation (chemistry)IonZeitschrift f�r Physik D Atoms, Molecules and Clusters
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Analysis of Localized Surface Plasmon Resonances in Spherical Jellium Clusters and Their Assemblies

2017

Due to multiple possible applications of physico-chemical properties of plasmonic metal nanoparticles and particle systems, there is high interest to understand the mechanisms that underlie the birth of localized surface plasmon resonance (LSPR). Here we studied the birth of the LSPR in spherical jellium clusters with the density of sodium and with 8, 20, 34, 40, 58, 92, 138, and 186 electrons, by using the linear response time-dependent density functional theory (lr-TDDFT). The coupling of the individual plasmon resonances in dimer, trimer, tetramer, and hexamer cluster assemblies consisting of the 8-electron cluster was also studied. The Kohn-Sham electron-hole transitions contributing to…

Jellium02 engineering and technologyElectron010402 general chemistry01 natural sciencesPhysics::Atomic and Molecular ClustersCluster (physics)Physical and Theoretical ChemistrySurface plasmon resonancePerturbation theoryta116Plasmonta114Chemistrysurface plasmons021001 nanoscience & nanotechnology0104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsGeneral EnergynanohiukkasetnanoparticlesDensity functional theoryAtomic physics0210 nano-technologyLocalized surface plasmonThe Journal of Physical Chemistry C
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Nuclear shell model applied to metallic clusters

1993

We apply the nuclear shell model to jellium clusters of up to twenty-one Na atoms. Binding energies, ionization potentials, and photoabsorption cross sections are calculated and compared with mean-field results.

Materials scienceIonizationNuclear TheoryJelliumBinding energyMetallic clustersPhysics::Atomic and Molecular ClustersNuclear shell modelPhysics::Atomic PhysicsElectronic structureAtomic physicsIonization energyAtomic and Molecular Physics and OpticsZeitschrift f�r Physik D Atoms, Molecules and Clusters
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Electronic structure of MgO-supported Au clusters: quantum dots probed by scanning tunneling microscopy.

2007

We investigate via density functional theory (DFT) the appearance of small MgO-supported gold clusters with 8 to 20 atoms in a scanning tunneling microscope (STM) experiment. Comparison of simulations of ultrathin films on a metal support with a bulk MgO leads to similar results for the cluster properties relevant for STM. Simulated STM pictures show the delocalized states of the cluster rather than the atomic structure. This finding is due to the presence of s- derived delocalized states of the cluster near the Fermi energy. The properties of theses states can be understood from a jellium model for monovalent gold.

Materials scienceJelliumScanning tunneling spectroscopyGeneral Physics and AstronomySpin polarized scanning tunneling microscopyConductive atomic force microscopyMolecular physicsElectrochemical scanning tunneling microscopelaw.inventionCondensed Matter::Materials ScienceDelocalized electronlawCondensed Matter::SuperconductivityPhysics::Atomic and Molecular ClustersCluster (physics)Atomic physicsScanning tunneling microscopePhysical review letters
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Role of Donor and Acceptor Substituents on the Nonlinear Optical Properties of Gold Nanoclusters

2018

In recent years, a large number of monolayer-protected clusters (MPCs) have been studied by means of single crystal structure characterization. A central aspect of research on MPCs is the correlation of their interesting optical properties with structural features and the formulation of a theoretical framework that allows interpretation of their unique properties. For this, superatom and jellium models have been proven successful. Little attention, however, has been paid to the influence of the protecting ligands. Here, we investigate the effect of changes in [Au25(SR)18-x(SR′)x]−, where SR′ represents a para-substituted thiophenolate derivative (SPh-4-X). We computed the first hyperpolariz…

Materials scienceJelliumnanoclustersSubstituent02 engineering and technology010402 general chemistrygold clusters01 natural sciencesmonolayer-protected clustersNanoclusterschemistry.chemical_compoundPhysical and Theoretical Chemistryta116ta114ThiophenolSuperatomgoldOrders of magnitude (numbers)021001 nanoscience & nanotechnologyAcceptor0104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsCrystallographyGeneral Energychemistry0210 nano-technologySingle crystalThe Journal of Physical Chemistry C
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Electronic polarizability of small sodium clusters.

1986

Abstract : Small sodium clusters consisting of 1 to 40 atoms are described as spheres of interacting homogeneous electron gas (jellium model). The static electronic polarizability is calculated using self consistent density functional methods. An excellent agreement with recent experimental results is observed.

Materials sciencechemistryPolarizabilityHomogeneousSodiumJelliumHomogeneity (physics)Physics::Atomic and Molecular Clusterschemistry.chemical_elementSPHERESAtomic physicsFermi gasPolarization (waves)Physical review. B, Condensed matter
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Electron-positron density-functional theory.

1986

A two-component density-functional theory is presented for electron-positron systems. The phase diagram of a two-component Fermi-Coulomb system is discussed, and explicit expressions are derived for exchange-correlation functionals for use in the local-density approximation. The scheme is then applied in a fully self-consistent calculation of electron and positron densities in atomic vacancies in metals, treated in the jellium model. Comparison with conventional calculations, which do not meet true electron-positron self-consistency, reveals considerable changes in the density distributions. However, we demonstrate that there are cancellation effects which render the corresponding changes i…

PhysicsAnnihilationPositronQuantum mechanicsJelliumObservableDensity functional theoryElectronPhase diagramPhysical review. B, Condensed matter
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