Shape transition region implied in the light Nb isotopes: Excited states inNb83

C. J. Gross; W. Gelletly; M. A. Bentley; H. G. Price; J. Simpson; B. J. Varley; J. L. Durell; Ö. Skeppstedt; S. Rastikerdar

doi:10.1103/physrevc.43.r5

Connecting the X(5)-β2, X(5)-β4, and X(3) models to the shape/phase transition region of the Interacting Boson Model

HNPS Proceedings ◽

10.12681/hnps.2628 ◽

2020 ◽

Vol 15 ◽

pp. 118

Author(s):

E. A. McCutchan ◽

D. Bonatsos ◽

R. F. Casten

Keyword(s):

Phase Transition ◽

Transition Region ◽

Interacting Boson Model ◽

Shape Transition ◽

Scale Factors ◽

Phase Transition Region ◽

Boson Model ◽

Shape Phase Transition ◽

Two Parameter ◽

Boson Approximation

The parameter independent (up to overall scale factors) predictions of the X(5)-β2, X(5)-β4, and X(3) models, which are variants of the X(5) critical point symmetry developed within the framework of the geometric collective model, are compared to two- parameter calculations in the framework of the interacting boson approximation (IBA) model. The results show that these geometric models coincide with IBA parameters consistent with the phase/shape transition region of the IBA for boson numbers of physical interest (close to 10). 186Pt and 172Os are identified as good examples of X(3), while 146Ce, 174Os and 158Er, 176Os are identified as good examples of X(5)-β2 and X(5)-β4 behavior respectively.

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GLOBAL GEOMETRY OPTIMIZATION OF SILICON CLUSTERS EMPLOYING EMPIRICAL POTENTIALS, DENSITY FUNCTIONALS, AND AB INITIO CALCULATIONS

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633605002008 ◽

2005 ◽

Vol 04 (04) ◽

pp. 1119-1151 ◽

Cited By ~ 12

Author(s):

ADEM TEKIN ◽

BERND HARTKE

Keyword(s):

Ab Initio Calculations ◽

Ab Initio ◽

Transition Region ◽

Basis Set ◽

Silicon Cluster ◽

Shape Transition ◽

Silicon Clusters ◽

Empirical Potentials ◽

Cluster Shape ◽

Spherical Structures

Si n clusters in the size range n = 4–30 have been investigated using a combination of global structure optimization methods with DFT and ab initio calculations. One of the central aims is to provide explanations for the structural transition from prolate to spherical outer shapes at about n = 25, as observed in ion mobility measurements. Firstly, several existing empirical potentials for silicon and a newly generated variant of one of them were better adapted to small silicon clusters, by global optimization of their parameters. The best resulting empirical potentials were then employed in global cluster structure optimizations. The most promising structures from this stage were relaxed further at the DFT level with the hybrid B3LYP functional. For the resulting structures, single point energies have been calculated at the LMP2 level with a reasonable medium-sized basis set, cc-pVTZ. These DFT and LMP2 calculations were also carried out for the best structures proposed in the literature, including the most recent ones, to obtain the currently best and most complete overall picture of the structural preferences of silicon clusters. In agreement with recent findings, results obtained at the DFT level do support the shape transition from prolate to spherical structures, beginning with Si 26 (albeit not completely without problems). In stark contrast, at the LMP2 level, the dominance of spherical structures after the transition region could not be confirmed. Instead, just as below the transition region, prolate isomers are obtained as the lowest-energy structures for n ≤ 29. We conclude that higher (probably multireference) levels of theoretical treatments are needed before the puzzle of the silicon cluster shape transition at n = 25 can safely be considered as explained.

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The Folding of Triangulated Cylinders, Part II: The Folding Process

Journal of Applied Mechanics ◽

10.1115/1.2901554 ◽

1994 ◽

Vol 61 (4) ◽

pp. 778-783 ◽

Cited By ~ 31

Author(s):

S. D. Guest ◽

S. Pellegrino

Keyword(s):

Transition Region ◽

Strain Energy ◽

Peak Force ◽

Second Phase ◽

Peak Strain ◽

Shape Transition ◽

Zero Force ◽

Folding Process ◽

Two Phases ◽

The Way

In the first paper of this series we have introduced a class of foldable triangulated cylinders. In this paper we consider three particular examples of these cylinders and analyse computationally the way they fold. We show that this process is nonuniform and that it consists of two phases. The first unsteady phase involves the gradual buildup of strain energy in a “shape transition region.” In the second phase the transition region moves toward the bottom of the cylinder under almost zero force. Although the behavior of the three example cylinders is qualitatively similar, the peak force on the cylinder, as well as the peak strain, have different magnitudes, in agreement with a result in our first paper.

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Excited states in 196Os and the structure of the PtOs transition region

Physics Letters B ◽

10.1016/0370-2693(83)91034-1 ◽

1983 ◽

Vol 130 (3-4) ◽

pp. 167-170 ◽

Cited By ~ 24

Author(s):

P.D. Bond ◽

R.F. Casten ◽

D.D. Warner ◽

D. Horn

Keyword(s):

Transition Region ◽

Excited States

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Effects of Ambipolar Diffusion on Prominence Thread Models

International Astronomical Union Colloquium ◽

10.1017/s0252921100025513 ◽

1994 ◽

Vol 144 ◽

pp. 315-321 ◽

Cited By ~ 1

Author(s):

M. G. Rovira ◽

J. M. Fontenla ◽

J.-C. Vial ◽

P. Gouttebroze

Keyword(s):

Energy Balance ◽

Transition Region ◽

Ambipolar Diffusion ◽

Line Profiles ◽

Balance Equations ◽

Model Calculations ◽

Partial Frequency ◽

Frequency Redistribution ◽

Partial Frequency Redistribution ◽

Theoretical Structure

AbstractWe have improved previous model calculations of the prominence-corona transition region including the effect of the ambipolar diffusion in the statistical equilibrium and energy balance equations. We show its influence on the different parameters that characterize the resulting prominence theoretical structure. We take into account the effect of the partial frequency redistribution (PRD) in the line profiles and total intensities calculations.

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Vuv Spectra Y to Mo

International Astronomical Union Colloquium ◽

10.1017/s0252921100107808 ◽

1988 ◽

Vol 102 ◽

pp. 239

Author(s):

M.S.Z. Chaghtai

Keyword(s):

Excited States ◽

Spectral Analyses ◽

Vuv Spectra

Using R.D. Cowan’s computations (1979) and parametric calculations of Meinders et al (1982), old analyses are thoroughly revised and extended at Aligarh, of Zr III by Khan et al (1981), of Nb IV by Shujauddin et Chaghtai (1985), of Mo V by Tauheed at al (1985). Cabeza et al (1986) confirmed the last one largely.Extensive studies have been reported of the 1–e spectra, Zr IV (Rahimullah et al 1980; Acquista and Reader 1980), Nb V (Shujauddin et al 1982; Kagan et al 1981) and Mo VI (Edlén et al 1985). Some interacting 4p54d2levels of these spectra have been reported from our laboratory, also.Detailed spectral analyses of transitions between excited states have furnished complete energy values for J ≠ 1 levels of these spectra during 1970s and 80s. Shujauddin et al (1982) have worked out Nb VI and Tauheed et al (1984) Mo VII from our lab, while Khan et al (1981) share the work on Zr V with Reader and Acquista (1979).

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