Small clusters: between dynamics and thermodynamics

Berry, R. S.

doi:10.1007/bf01426929

Cited by 18 publications

(2 citation statements)

References 9 publications

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“…Over the past two decades considerable effort has gone into understanding properties of free clusters. − Their properties have been studied in great detail, and many good reviews exist on this topic. − However, clusters are not always found in their free form. They are often found to be enclosed in some host matrixan inorganic or organic porous solidor simply attached to a substrate.…”

Section: Introductionmentioning

confidence: 99%

Inverse Surface Melting in Confined Clusters: Ar₁₃in Zeolite L

Читра

Yashonath

1997

J. Phys. Chem. B

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Monte Carlo and molecular dynamics simulations on an Ar 13 cluster in zeolite L have been carried out at a series of temperatures to understand the rigid-nonrigid transition corresponding to the solid-liquid transition exhibited by the free Ar 13 cluster. The icosahedral geometry of the free cluster is no longer preferred when the cluster is confined in the zeolite. The root-mean-squared pair distance fluctuation, δ, exhibits a sharp, well-defined rigid-nonrigid transition at 17 K as compared to 27 K for the free cluster. Multiple peaks in the distribution of short-time averages of the guest-host interaction energy indicate coexistence of two phases. It is shown that this transition is associated with the inner atoms becoming mobile at 17 K even while the outer layer atoms, which are in close proximity to the zeolitic wall, continue to be comparatively immobile. This may be contrasted with the melting of large free clusters of 40 or more atoms which exhibit surface melting. Guest-host interactions seem to play a predominant role in determining the properties of confined clusters. We demonstrate that the volume of the cluster increases rather sharply at 17 and 27 K respectively for the confined and the free cluster. Power spectra suggest that the motion of the inner atoms is generally parallel to the atoms which form the cage wall.

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Section: Introductionmentioning

confidence: 99%

Inverse Surface Melting in Confined Clusters: Ar₁₃in Zeolite L

Читра

Yashonath

1997

J. Phys. Chem. B

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“…Considerable interest has been shown in the study of formation and stucture of clusters [1][2][3][4][5][6][7]. Special attention has been paid also to the phase transitions of clusters according to the idea that the stucture of cluster is also important for its stability [8,9]. A number of experiments have been focused on the problem of cluster properties such as ionization potentials, crystallographic structure, binding energy, chemical reactivity, and its dependence on the particle size known as the "quantum size" effect [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Size Evolution of the Light Induced Sodium Clusters

et al. 1992

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We report the observation of the size evolution of the laser light formed clusters. A cell containing sodium vapor and the buffer gas (He) under high pressure was used in the experiment. Changes of the radius and of the density of transient clusters were observed via the time evolution of the intensity of right-angle scattered light. The rate of the cluster radius growth was found to vary from 0.012 to 0.1 μm/s.

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Auf dem Weg zur Syntheseplanung in der Festkörperchemie: Vorhersage existenzfähiger Strukturkandidaten mit Verfahren zur globalen Strukturoptimierung

Schön¹,

Jansen²

1996

Angewandte Chemie

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Wir stellen hier eine Methode vor, mit der im Prinzip die Existenz und Struktur von (meta)stabilen Festkörperverbindungen vorhergesagt werden kann. Sie beruht auf der Erkundung der Energiefunktion des betrachteten chemischen Systems mit Verfahren, die zunächst eine globale und schließlich eine lokale Optimierung ermöglichen. Das hierfür entwickelte Programmsystem ist modular aufgebaut. Die Hauptelemente sind eine Reihe von Routinen für globale und lokale Minimierungen sowie Algorithmen zur Untersuchung der Phasenraumstruktur in der Nähe lokaler Minima der potentiellen Energie und zur Analyse und Charakterisierung der Strukturkandidaten. Derzeit behandeln wir damit ionische Verbindungen, wobei die Energiefunktion zunächst mit Hilfe empirischer Potentiale berechnet wird und danach die Ergebnisse mit einem Hartree‐Fock‐Algorithmus verfeinert werden. Die globale Optimierung erfolgt mit einem stochastischen «Simulated‐Annealing»‐Algorithmus, die lokale Minimierung verwendet einen stochastischen «Quench» oder ein Gradientenverfahren. Die Umgebungen der lokalen Minima werden mit dem «Threshold»‐Algorithmus untersucht. Wir zeigen Ergebnisse dieses Ansatzes an binären Mischphasen der Edelgase sowie an binären und ternären ionischen Systemen. Diese schließen einige bislang noch nicht synthetisierte Substanzen ein, die jedoch kinetisch stabil sein sollten, z.B. weitere Alkalimetallnitride neben Li3N sowie Ca3SiBr2 und SrTi2O5.

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Small clusters: between dynamics and thermodynamics

Cited by 18 publications

References 9 publications

Inverse Surface Melting in Confined Clusters: Ar₁₃in Zeolite L

Inverse Surface Melting in Confined Clusters: Ar₁₃in Zeolite L

Size Evolution of the Light Induced Sodium Clusters

Auf dem Weg zur Syntheseplanung in der Festkörperchemie: Vorhersage existenzfähiger Strukturkandidaten mit Verfahren zur globalen Strukturoptimierung

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Small clusters: between dynamics and thermodynamics

Cited by 18 publications

References 9 publications

Inverse Surface Melting in Confined Clusters: Ar13in Zeolite L

Inverse Surface Melting in Confined Clusters: Ar13in Zeolite L

Size Evolution of the Light Induced Sodium Clusters

Auf dem Weg zur Syntheseplanung in der Festkörperchemie: Vorhersage existenzfähiger Strukturkandidaten mit Verfahren zur globalen Strukturoptimierung

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Inverse Surface Melting in Confined Clusters: Ar₁₃in Zeolite L

Inverse Surface Melting in Confined Clusters: Ar₁₃in Zeolite L