Microscopic analysis of shape evolution and triaxiality in germanium isotopes

Nikšić, Tamara and Marević, P. and Vretenar, Dario (2014) Microscopic analysis of shape evolution and triaxiality in germanium isotopes. Physical Review C, 89 (4). pp. 44325-8. ISSN 0556-2813

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Background: The motivation for this study is the experimental evidence for rigid triaxial deformation at low energy in ^76Ge that was recently observed. Purpose: Quadrupole shapes and low-energy spectra of the isotopes ^72–82Ge are analyzed using a theoretical framework based on nuclear density functional theory. Method: The relativistic functional DD-PC1, supplemented by a finite-range pairing force, is used to perform constrained triaxial mean-field calculations of energy surfaces as functions of quadrupole deformation parameters. The corresponding collective Hamiltonian, based on DD-PC1, is employed in the calculation of excitation spectra and transition rates. Results: Model calculations reproduce the empirical trend of collective observables and predict the evolution of shapes from weakly triaxial in ^74Ge to γ soft in ^78,80Ge. For ^76Ge, in particular, the theoretical excitation spectrum is in good agreement with available data, the experimental ratio E(2^+_2)/E(2^+_1) is reproduced, as well as the pattern and amplitude of the staggering in energy between odd- and even-spin states in the γ band. Conclusions: The mean-field potential of ^76Ge appears to be γ soft. Collective correlations drive the nucleus toward triaxiality but do not stabilize a rigid triaxial shape. Both the experimental and theoretical staggering of levels in the γ band display a pattern consistent with triaxial shapes but the amplitudes are negligible and do not present evidence for rigid triaxiality.

Item Type: Article
Date: April 2014
Subjects: NATURAL SCIENCES > Physics
Additional Information: Copyright (2014) by the American Physical Society.
Divisions: Faculty of Science > Department of Physics
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 26 Aug 2014 12:18
Last Modified: 26 Aug 2014 12:18
URI: http://digre.pmf.unizg.hr/id/eprint/2382

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