Hückel model for metal clusters: Ground states and low energy isomers

Yoshida, Atsushi; Døssing, T.; Manninen, M.

doi:10.1063/1.467617

Cited by 22 publications

(19 citation statements)

References 29 publications

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“…The same result has been obtained with the ellipsoidal jellium models [11,12], and also with more general jellium-type models [13,15] and the simple Hiickel model [43,44]. This pattern, however, is expected to change after N = 40 so that the shape is oblate at the beginning of a shell and prolate at the end [13,15].…”

Section: T Ground-state Geometries"supporting

confidence: 75%

Electron-gas clusters: the ultimate jellium model

Koskinen

Lipas

Manninen³

1995

Z Phys D - Atoms, Molecules and Clusters

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105

112

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Abstract. The local spin-density approximation is used to calculate ground-and isomeric-state geometries ofjellium clusters with 2 to 22 electrons. The positive background charge of the model is completely deformable, both in shape and in density. The model has no input parameters. The resulting shapes of the clusters exhibit breaking of axial and inversion symmetries; in general the shapes are far from ellipsoidal. Those clusters which lack inversion symmetry are extremely soft against odd-multipole deformations. Some clusters can be interpreted as molecules built from magic clusters. The deformation produces a gap at the Fermi level. This results in a regular odd-even staggering of the total energy per electron and of the HOMO level. The strongly deformed 14-electron cluster is semimagic. Stable isomers are predicted. The splitting of the plasmon resonance due to deformation is estimated on a classical argument.

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Section: T Ground-state Geometries"supporting

confidence: 75%

Electron-gas clusters: the ultimate jellium model

Koskinen

Lipas

Manninen³

1995

Z Phys D - Atoms, Molecules and Clusters

Self Cite

105

112

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“…(2) should not be confused with the most stable geometries determined with the true tight-binding method. [30,31] The Monte Carlo simulations are performed using the PP model energy expression Eq. (1), which leads in many cases to several different geometries with the same energy.…”

Section: A Monte Carlo Methods For Hard Sphere Clustersmentioning

confidence: 99%

Close packing of clusters: Application toAl100

2003

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The lowest energy configurations of close-packed clusters up to N = 110 atoms with stacking faults are studied using the Monte Carlo method with a Metropolis algorithm. Two types of contact interactions, a pair-potential and a many-atom interaction, are used. Enhanced stability is shown for N = 12, 26, 38, 50, 59, 61, 68, 75, 79, 86, 100 and 102, of which only the sizes 38, 75, 79, 86, and 102 are pure FCC clusters, the others having stacking faults. A connection between the model potential and density functional calculations is studied in the case of Al100. The density functional calculations are consistent with the experimental fact that there exist epitaxially grown FCC clusters starting from relatively small cluster sizes. Calculations also show that several other close-packed motifs exist with comparable total energies.

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“…For Na 10 , the bicapped antiprism, the lowest energy structure found in [4], was employed. The simulation study for Na 14 was started from a prolate structure [18] consisting of three stacked squares, the middle one rotated by π/4 with respect to the others, and two atoms at the ends. The starting configuration for Na + 55 was a complete icosahedron from which one electron was removed.…”

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confidence: 99%

Melting and multipole deformation of sodium clusters

Rytkönen

Häkkinen

Manninen

1999

The European Physical Journal D

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Melting and multipole deformations of sodium clusters with up to 55 atoms are studied using an ab initio molecular dynamics method. The melting temperature regions for Na 20 , Na 40 , and Na + 55 are estimated. The melting temperature region determined here for Na + 55 agrees with the one determined experimentally. The dominating deformation type observed at the liquid phase for Na 20 and Na 40 is octupole deformation and for Na 14 and Na + 55 quadrupole deformation. PACS. 36.40.Cg Electronic and magnetic properties of clusters -36.40.Ei Phase transitions in clusters -36.40.Mr Spectroscopy and geometrical structure of clustersMelting and structural properties of small clusters have been studied intensively during the last years using various numerical and experimental techniques [1][2][3]. Recent introduction of ab initio methods for studying geometric and electronic structure in alkali metal clusters [4][5][6], along with tight-binding calculations and molecular dynamics simulations with many-body potential [7,8], has provided new detailed information about their finite-temperature properties. In our recent study [6], electronic and structural properties of Na 40 were studied using an ab initio method [9]. Na 40 was found to melt around 300-350 K and was found to be dominantly octupole deformed. Development in experimental cluster physics has enabled the study of melting transition in metal clusters with less than 100 atoms. Melting temperatures of sodium clusters with 55-200 atoms were determined experimentally recently [10][11][12]. The results of ab initio calculations and experiments of melting behaviour of small sodium clusters can now be compared directly.In this paper we have studied the finite-temperature dynamics of sodium clusters containing 8-55 atoms, including both electronic and structural properties, with ab initio BO-LSD-MD (Born-Oppenheimer Local-SpinDensity Molecular Dynamics) method devised by Barnett and Landman [9]. Both magic and non-magic clusters were included in the study. The melting temperature regions obtained here for Na 20 , Na 40 and Na + 55 were found to increase monotonically as a function of particle number. For smaller sodium clusters with 8, 10, and 14 atoms, however, a melting temperature region could not be convincingly identified with traditional indicators. Na 20 and Na 40 were principally octupole deformed at the whole temperature region studied. Na 14 was found to be prolate at 50-450 K, and Na + 55 was prolate at temperatures above its melting region.In the BO-LSD-MD method, the Kohn-Sham (KS) one-electron equations for the single-electron states of the valence electrons are solved for a given nuclear configuration of the ions. From the converged solution the Hellmann-Feynmann forces to the ions are calculated, which together with the classical Coulomb repulsion between the positive ion cores determine the total forces to the ions, according to which classical molecular dynamics for the ions is performed. The fully converged solution for the electronic structure is obt...

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Hückel model for metal clusters: Ground states and low energy isomers

Cited by 22 publications

References 29 publications

Electron-gas clusters: the ultimate jellium model

Electron-gas clusters: the ultimate jellium model

Close packing of clusters: Application toAl100

Melting and multipole deformation of sodium clusters

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