Speaker
Description
With the commissioning of next-generation radioactive ion beam facilities worldwide, nuclear structure physics has entered a new era of opportunities. The exploration of exotic nuclei far from stability has revealed a variety of unexpected phenomena, including octupole (pear-shaped) deformation, tetrahedral symmetry, and asymmetric fission in the sub-lead region, highlighting the remarkable richness of nuclear many-body systems. These discoveries have significantly broadened our understanding of atomic nuclei while posing stringent challenges to microscopic nuclear theories.
Motivated by these frontier problems, we develop a series of microscopic collective Hamiltonian models based on covariant density functional theory to investigate nuclear collective excitations and fission dynamics:
1. Using the five-dimensional quadrupole collective Hamiltonian (5DCH), we systematically investigate the influence of quantum shape fluctuations on the structure of superheavy nuclei and demonstrate that they substantially reduce the stability of superheavy nuclei in transitional regions [1].
2. By extending the framework to incorporate octupole collective degrees of freedom, we achieve a unified description of negative-parity rotational bands in lanthanide and actinide nuclei [2-4], predict stable tetrahedral configurations around $^{110}\mathrm{Zr}$, and identify characteristic low-lying spectroscopic signatures to guide future experimental searches [5].
3. Furthermore, a time-dependent extension of the collective Hamiltonian successfully reproduces the recently observed asymmetric fission mode in the $^{180}\mathrm{Hg}$ region and reveals that it originates from the cooperative interplay between the deformed proton shell gap at $Z\approx36$ and the octupole neutron shell closure at $N\approx56$ [6,7].
These results establish a unified microscopic framework for describing collective phenomena in exotic nuclei, providing new insights into the emergence of novel nuclear shapes and fission dynamics. They also offer theoretical guidance for experiments at current and next-generation radioactive ion beam facilities.
Reference
[1] X. Q. Yang, R. Y. Hu, R.N. Mao, J. Xiang, and Z.P. Li, Systematic study of superheavy nuclei within a microscopic collective Hamiltonian: Impact of quantum shape fluctuations, Phys. Lett. B 876, 140382 (2026)
[2] S. Y. Xia, H. Tao, Y. Lu, Z. P. Li, T. Nikšić, and D. Vretenar, Spectroscopy of reflection-asymmetric nuclei with relativistic energy density functionals, Phys. Rev. C 96, 054303 (2017).
[3] W. Sun, S. Quan, Z. P. Li, J. Zhao, T. Nikšić, and D. Vretenar, Microscopic core-quasiparticle coupling model for spectroscopy of odd-mass nuclei with octupole correlations. Phys. Rev. C 100, 044319(2019).
[4] J. Xiang, J. Zhao, Z. P. Li, and D. Vretenar, Microscopic triaxial quadrupole-octupole collective Hamiltonian for low-energy nuclear excitations, Phys. Rev. C 113, 044328 (2026).
[5] J. Xiang, J. Zhao, Z. P. Li, and D. Vretenar, Tetrahedra symmetry in atomic nuclei, in preparation.
[6] Z. Y. Li, S. Y. Chen, Y. J. Chen, and Z. P. Li, Microscopic study on asymmetric fission dynamics of 180Hg within covariant density functional theory, Phys. Rev. C 106, 024307 (2022).
[7] S. Y. Chen, Z. Y. Li, M. H. Zhou, Y. J. Chen, and Z. P. Li, In preparation.