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Fragmentation Phase Transition in Atomic Clusters II -----Symmetry of Fission of Metal Clusters----  [PDF]
M. E. Madjet,P. A. Hervieux,D. H. E. Gross,O. Schapiro
Physics , 1996, DOI: 10.1007/s004600050141
Abstract: We present a statistical fragmentation study of doubly charged alkali (Li, Na, K) and antimony clusters. The evaporation of one charged trimer is the most dominant decay channel (asymmetric fission) at low excitation energies. For small sodium clusters this was quite early found in molecular dynamical calculations by Landman et al. For doubly charged lithium clusters, we predict Li$_{9}^{+}$ to be the preferential dissociation channel. As already seen experimentally a more symmetric fission is found for doubly charged antimony clusters. This different behavior compared to the alkali metal clusters is in our model essentially due to a larger fissility of antimony. This is checked by repeating the calculations for Na$_{52}^{++}$ with a bulk fissility parameter set artificially equal to the value of Sb.
Time resolved fission in metal clusters  [PDF]
P. M. Dinh,P. -G. Reinhard,E. Suraud
Physics , 2004, DOI: 10.1088/0953-4075/38/11/005
Abstract: We explore from a theoretical point of view pump and probe (P&P) analysis for fission of metal clusters where probe pulses are generalized to allow for scanning various frequencies. We show that it is possible to measure the time the system needs to develop to scission. This is achieved by a proper choice of both delay and frequency of the probe pulse. A more detailed analysis even allows to access the various intermediate stages of the fission process.
Dissociation, fragmentation and fission of simple metal clusters  [PDF]
Constantine Yannouleas,Uzi Landman,Robert N. Barnett
Physics , 1999,
Abstract: This pedagogical review presents the Shell Correction Method (SCM) and variants thereof, appropriate for describing shape deformations and electronic shell effects, energetics and decay pathways of metal-cluster fragmentation processes (e.g., monomer/dimer dissociation and fission). The experimental trends are compared to the theoretical SCM interpretations, and in addition theoretical results for fission from first-principles molecular-dynamics simulations are discussed. Some latest insights concerning the importance of electronic-entropy and finite-temperature effects are given special attention.
Statistical measures applied to metal clusters: evidence of magic numbers  [PDF]
Jaime Sanudo,Ricardo Lopez-Ruiz
Physics , 2010,
Abstract: In this work, a shell model for metal clusters up to 220 valence electrons is used to obtain the fractional occupation probabilities of the electronic orbitals. Then, the calculation of a statistical measure of complexity and the Fisher-Shannon information is carried out. An increase of both magnitudes with the number of valence electrons is observed. The shell structure is reflected by the behavior of the statistical complexity. The magic numbers are indicated by the Fisher-Shannon information. So, as in the case of atomic nuclei, the study of statistical indicators also unveil the existence of magic numbers in metal clusters.
Comparative study of metal cluster fission in Hartree-Fock and LDA  [PDF]
Andrey Lyalin,Andrey Solov'yov,Walter Greiner
Physics , 2001, DOI: 10.1103/PhysRevA.65.043202
Abstract: Fission of doubly charged metal clusters is studied using the open-shell two-center deformed jellium Hartree-Fock model and Local Density Approximation. Results of calculations of the electronic structure and fission barriers for the symmetric and asymmetric channels associated with the following processes Na_{10}^{2+} --> Na_{7}^{+} + Na_{3}^{+}, Na_{18}^{2+} --> Na_{15}^{+} + Na_{3}^{+} and Na_{18}^{2+} --> 2 Na_{9}^{+} are presented. The role of the exact exchange and many-body correlation effects in metal clusters fission is analysed. It is demonstrated that the influence of many-electron correlation effects on the height of the fission barrier is more profound if the barrier arises nearby or beyond the scission point. The importance of cluster deformation effects in the fission process is elucidated with the use of the overlapping-spheroids shape parametrization allowing one an independent variation of deformations in the parent and daughter clusters.
Statistical Model of Heavy-Ion Fusion-Fission Reactions  [PDF]
J. P. Lestone,S. G. McCalla
Physics , 2008, DOI: 10.1103/PhysRevC.79.044611
Abstract: Cross-section and neutron-emission data from heavy-ion fusion-fission reactions are consistent with the fission of fully equilibrated systems with fission lifetime estimates obtained via a Kramers-modified statistical model which takes into account the collective motion of the system about the ground state, the temperature dependence of the location and height of fission transition points, and the orientation degree of freedom. If the standard techniques for calculating fission lifetimes are used, then the calculated excitation-energy dependence of fission lifetimes is incorrect. We see no evidence to suggest that the nuclear viscosity has a temperature dependence. The strong increase in the nuclear viscosity above a temperature of approximately 1.3 MeV deduced by others is an artifact generated by an inadequate fission model.
Fragmentation of multiply charged simple metal clusters in liquid-drop stabilized jellium model  [PDF]
M. Payami
Physics , 2003, DOI: 10.1002/pssb.200302029
Abstract: In this work, we have used the liquid-drop model in the context of stabilized jellium model, to study the stability of $Z$-ply charged metal clusters of different species against fragmentation. We have shown that on the one hand, singly ionized clusters are stable against any spontaneous fragmentation, and on the other hand, the most favored decay process for them is atomic evaporation. However, multiply charged clusters of sufficiently small sizes may undergo spontaneous decay via fission processes. Comparing the results for different species show that for fixed $N$, the lower electron density metal clusters can accommodate more excess charges before their Coulomb explosions. This comparison also shows that, for fixed $Z$, the atomic evaporation which is the most favored decay mechanism for sufficiently large clusters, takes place at lower $N$s for lower electron density clusters.
Evaluation of excitation energy and spin in fission fragments using the statistical model, and the FIPPS project  [cached]
Faust H.,Kessedjian G.,Sage C.,Koester U.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134206004
Abstract: We review the statistical model and its application for the process of nuclear fission. The expressions for excitation energy and spin distributions for the individual fission fragments are given. We will finally emphasize the importance of measuring prompt gamma decay to further test the statistical model in nuclear fission with the FIPPS project.
Dual Statistical Systems and Geometrical String  [PDF]
G. K. Savvidy,K. G. Savvidy,P. G. Savvidy
Physics , 1994, DOI: 10.1016/0375-9601(96)00541-5
Abstract: We analyse statistical system with interface energy proportional to the length of the edges of interface. We have found the dual system high temperature expansion of which equally well generates surfaces with linear amplitude. These dual systems are in the same relation as 3D Ising ferromagnet to the 3D Gauge spin system.
Theory for Nonlinear Mie-Scattering from Spherical Metal Clusters  [PDF]
J. Dewitz,W. Hubner,K. H. Bennemann
Physics , 1994,
Abstract: Using classical electrodynamics we determine the angular dependence of the light intensities radiated in second and third harmonic generation by spherical metal clusters. Forward and backward scattering is analyzed in detail. Also resonance effects in the integrated intensities are studied. Our work treats the case of intermediate cluster sizes. Thus it completes the scattering theory fo spherical clusters between Rayleigh-type analysis for small spheres and geometrical optics for spheres much larger than the wavelength for nonlinear optics. Since the particle size sensitivity of Mie-scattering is increased by nonlinearity, the results can be used to extract sizes of small particles from nonlinear optics. (submitted to Phys. Rev. B)
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