Thermal quenching of electronic shells and channel competition in cluster fission

Physical Review Letters

Volumn 89, Issue 17, 2002, Pages 173403/1-173403/4

  Yannouleas, Constantine ^a   Landman, Uzi ^a   Brechignac C ^b   Cahuzac, P ^b   Concina, B ^b   Leygnier, J ^b  

^a GEORGIA INSTITUTE OF TECHNOLOGY   (United States)

^b LABORATOIRE AIMÉ COTTON   (France)

Author keywords

[No Author keywords available]

Indexed keywords

CALCULATIONS; ELECTRON TRANSITIONS; ELECTRONIC STRUCTURE; HIGH TEMPERATURE EFFECTS; LASER PULSES; LITHIUM; MASS SPECTROMETERS; NEODYMIUM LASERS; POSITIVE IONS; POTASSIUM; SODIUM; STABILITY;

CHANNEAL COMPETITION; CLUSTER FISSION; ELECTRONIC ENTROPY; ELECTRONIC SHELL EFFECTS; FINITE TEMPERATURE SHELL CORRECTION METHOD; MAGIC FRAGMENT CHANNELS; THERMAL QUENCHING;

FISSION REACTIONS;

EID: 0037152902     PISSN: 00319007     EISSN: None     Source Type: Journal    
DOI: 10.1103/PhysRevLett.89.173403     Document Type: Article

References (18)

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15. and it incorporates triaxial deformations, single-particle electronic entropy, and thermal averaging over the shape fluctuations. In the SCM approach, the total free energy of a finite system of interacting delocalized electrons is divided into two contributions: a part that varies smoothly with the system size and thus coincides with the LDM, and an oscillatory term accounting for the quantal shell effects. In keeping with the experimental analysis [13], the LDM curvature coefficients were taken to be zero, while the surface coefficients for Li, Na, and K were taken as 1.30, 0.85, and 0.70 eV, respectively. The temperature dependence of these coefficients was neglected. For the rest of coefficients of the FT-SCM, see the first part of this reference for Na and K, and C. Yannouleas and U. Landman, J. Chem. Phys. 107, 1032 (1997) for Li.
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18. 2+ clusters consist of vibrational and configurational terms. The latter is negligible for N < 50, and the former (modeled in our calculations via the cluster-shape fluctuations, see Ref. [12]) merely broadens the electronic density of states while maintaining the shell structure, even at elevated temperatures [O. B. Christensen et al., Phys. Rev. Lett. 66, 2219 (1991)]. This leaves the electronic entropy as the main factor influencing the thermal dependence of the shell structure and the distribution of fission products.