Statics and Stability of Small Cluster Nuclei

Hoare, M. R.; Pal, Poorna C.

doi:10.1038/physci230005a0

Cited by 69 publications

(37 citation statements)

References 8 publications

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“…The relative peak intensity , 1 Bragg ' may be calculat ed by the usual kinematical, expression for X-ray powder pattern '~ wi th a smal l angle approximation, 2 2 2M 1 Bragg I' hk1I 'P hJrl'dh~l 'e ~~I kin 'e~~ (4) I ~' hklI ~~~~f j . exp (2ni(hx~ + kY j 1 1z~)) 4f (5) ,wh ere f j is the elastic atomic scattering factor of electron for the ~t h atom with a coordinate ( x~.…”

Section: Ii) Peak Intens I Tymentioning

confidence: 99%

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Lead microclusters in the vapor phase as studied by molecular beam electron diffraction: Vestige of amorphous structure

Yokozeki¹

1978

The Journal of Chemical Physics

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The metal microclusters are formed in the gas phase by an isobaric cooling due to argon carrier gas, followed by adiabatic expansions through nozzle apertures. Electron diffraction patterns of these condensates show the typical Debye–Scherrer rings for the fcc Pb metal. The average size of clusters obtained, depending on the experimental conditions, ranges from 30 to 100 Å in diameter, and the cubic lattice parameters for these clusters are essentially the same, within an experimental error of 0.3%, as that for the bulk crystal. The analysis of the Bragg-peak intensities is carried out based on the usual kinematic theory and the dynamical (two-beam approximation) theory by Blackman. The former theory fails completely in accounting for small angle reflections (s≲5 Å−1), whereas the latter explains successfully the whole observe intensities, except for the second and third order reflections (400), (440), (333), and (600). From the damping of peak intensities the temperatures of these clusters are estimated to be of the order of 150 °K. A close inspection on the comparison between the observed and theoretical intensities, however, reveals periodic fluctuations in the observed peak heights as a function of the scattering angle, indicating a superposition of some diffuse scattering. The amplitudes of the fluctuations are more marked for the smaller size clusters. The characteristics of the fluctuations are accounted for by introducing liquidlike random atomic configurations into the microcrystalline. This model explains also the abnormal Bragg-peak intensities of Ar clusters reported in the literature.

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Section: Ii) Peak Intens I Tymentioning

confidence: 99%

“…~M~y aL ai' ..rr. 4 Office of Naval Research The metal microc lus ters are f armed in the gas phase by an isobaric cooling due to argon carrier gas , followed by adiabatic exp ansions through nozzle ap.~tu r es. Electron diffraction patterns of these condensates show the typical Debys-Sch.rrsr ring , for the f. c .…”

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confidence: 99%

Lead microclusters in the vapor phase as studied by molecular beam electron diffraction: Vestige of amorphous structure

Yokozeki¹

1978

The Journal of Chemical Physics

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“…In this way, one potential that has been used very often in those branches of the science is the Lennard-Jones potential, which is the topic studied in this paper. For instance, it is used to model the nature and stability of small clusters of interacting particles in crystal growth, random geometry of liquids and in the theory of homogeneous nucleation, see (Hoare and Pal, 1971) and (Wales and Doye, 1997). This potential also appears in molecular dynamics to simulate many particle systems ranging from solids, liquids, gases, and biomolecules on Earth.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium Points and Central Configurations for the Lennard-Jones 2- and 3-Body Problems

Corbera

Llibre

Pérez‐Chavela

2004

Celestial Mechanics and Dynamical Astronomy

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Abstract. In this paper we study the relative equilibria and their stability for a system of three point particles moving under the action of a Lennard-Jones potential. A central configuration is a special position of the particles where the position and acceleration vectors of each particle are proportional, and the constant of proportionality is the same for all particles. Since the Lennard-Jones potential depends only on the mutual distances among the particles, it is invariant under rotations. In a rotating frame the orbits coming from central configurations become equilibrium points, the relative equilibria. Due to the form of the potential, the relative equilibria depend on the size of the system, that is, depend strongly of the momentum of inertia I. In this work we characterize the relative equilibria, we find the bifurcation values of I for which the number of relative equilibria is changing, we also analyze the stability of the relative equilibria.

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“…15 It should be noted that LJ 26 is not the most challenging system among LJ n clusters because of peculiarities of the topology of PES of Lennard-Jones systems. For example, Wales and Doye 15 suggested that the efficiency of different methods should be estimated on their performance for LJ 38 and LJ 75 clusters, which have extremely complex PES. Definitely, these two computationally more demanding tasks are beyond the scope of the current article and can be addressed in future studies of the PSO technique.…”

Section: Computational Resultsmentioning

confidence: 99%

Global minimum structure searches via particle swarm optimization

2007

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Novel implementation of the evolutionary approach known as particle swarm optimization (PSO) capable of finding the global minimum of the potential energy surface of atomic assemblies is reported. This is the first time the PSO technique has been used to perform global optimization of minimum structure search for chemical systems. Significant improvements have been introduced to the original PSO algorithm to increase its efficiency and reliability and adapt it to chemical systems. The developed software has successfully found the lowest-energy structures of the LJ(26) Lennard-Jones cluster, anionic silicon hydride Si(2)H(5) (-), and triply hydrated hydroxide ion OH(-) (H(2)O)(3). It requires relatively small population sizes and demonstrates fast convergence. Efficiency of PSO has been compared with simulated annealing, and the gradient embedded genetic algorithm.

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Statics and Stability of Small Cluster Nuclei

Cited by 69 publications

References 8 publications

Lead microclusters in the vapor phase as studied by molecular beam electron diffraction: Vestige of amorphous structure

Lead microclusters in the vapor phase as studied by molecular beam electron diffraction: Vestige of amorphous structure

Equilibrium Points and Central Configurations for the Lennard-Jones 2- and 3-Body Problems

Global minimum structure searches via particle swarm optimization

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