arXiv subjects

Min-Liang Liu

Publications and source records attributed to Min-Liang Liu.

10 recordsLinked to original sources

arXiv2026

Revisiting the nuclear island of negative hexadecapole deformations in A$\approx$180 mass region: focusing on moments of inertia and quadrupole-hexadecapole coupling

For even-even nuclei $^{180-184}$Yb, $^{182-186}$Hf and $^{184-188}$W located on an island of hexadecapole-deformation archipelago, the structure properties, especially under rotation, are reinvestigated by using the Hartree-Fock-Bogliubov-Cranking (HFBC) calculation with a fixed shape (e.g., the ground-state equilibrium shape). The equilibrium deformations, extracted from the potential energy surface, are calculated based on the phenomenological Woods-Saxon mean-field Hamiltonian within the framework of macroscopic-microscopic (MM) model. The impact of different deformation degrees of freedom on, e.g., single-particle levels, total energy, and moment of inertia, is revealed, especially concentrating on the hexadecapole-deformation effects and the quadrupole-hexadecapole coupling. Considering the axially hexadecapole deformation, the present calculations can well reproduce available experimental data, including the quadrupole deformations and moments of inertia. Interestingly, it is found that the impact of different deformation degrees of freedom on moment of inertia exhibits a similar trend in the HFBC and rigid-body calculations though the latter ignores the pairing effects. Before starting or constructing a complex theory-model, to some extent, such a similarity can provide an alternative way of understanding the effect of, e.g., exotic deformations, on moment of inertia by the calculation of a simple rigid-body approximation. The present findings could offer insights into the static and dynamic effects of hexadecapole deformations, contributing valuable information for the corresponding research in nuclear structure and reaction.

nucl-th↗

arXiv2026

Probing the two-quasiparticle $K^π=8^+$ isomeric structure and enhanced stability in the proton drip-line nuclei

Stimulated by recent experimental discoveries [{Phys. Lett. B \textbf{847}, 138310 (2023)} and {Phys. Rev. Lett. \textbf{132}, 072502 (2024)}], two-quasiparticle $K^π=8^+$ isomeric structure (related to the neutron $h_{9/2}$ and $f_{7/2}$ orbitals) in $^{160}_{76}$Os$_{84}$ that lies at the two-proton drip line has been studied by means of the configuration-constrained potential-energy-surface calculations. Calculated results indicate that, for such an isomer, the excitation energy can be well reproduced and its oblate shape can be enhanced by the polarization effects of the two high-$K$ orbits. Comparing with experimental data, two sets of the widely used Woods-Saxon parameters, especially, the spin-orbit coupling one, are evaluated and argued. It is found that, considering the uncertainty of the spin-orbit coupling strength, the energy crossing or inversion of the $h_{9/2}$ and $f_{7/2}$ neutrons can occur, which may lead to three kinds of different evolution-trends of two-quasiparticle excitation energies with the changing quadrupole deformation $β_2$. With decreasing spin-orbit coupling interaction, the structure of the $K^π=8^+$ isomeric state will evolute from $νh_{9/2}f_{7/2}$ ($ν9/2^-[505] \otimes 7/2^-[503]$) to the mixing of $νh_{9/2}f_{7/2}$ and $νh_{9/2}^2$ ($ν9/2^-[505] \otimes 7/2^-[514]$) to $νh_{9/2}^2$, indicating that its structural probes is still of interest and an arbitrary assignment may be risky. The related theoretical calculations and experimental evidences e.g., the transition properties, are desirable. In addition, similar to that in superheavy nuclei, it is suggested that the stability inversion between high-$K$ isomeric states and ground states might occur in this proton drip-line mass region, e.g., in the hitherto unknown nucleus $^{162}_{78}$Pt$_{84}$.

nucl-th↗

arXiv2025

Probing the delicate balance of the spontaneous fission instability in sub-μs superheavy nucleus 252Rf

Stimulated by the recent experimental discovery of the sub-$μ$s fission nucleus $^{252}$Rf [Phys. Rev. Lett. 134 (2025) 022501], we perform an improved configuration-constrained potential-energy-surface calculation, revealing the mechanism of intricate balance for the enhanced stability due to the high-$K$ (e.g., $K^π= 6^+$) isomer, possibly building on a shape isomeric state. The different deformation and coupling effects, such as triaxial $γ$, reflection-asymmetric $β_{3}$ and high-order $β_{6}$ deformations, are discussed for both ground state and isomeric state based on the corresponding potential-energy curves along the fission valley. In particular, it is pointed out for the first time that possible multipath decay, e.g., from the high-$K$ isomeric state to those states formed between potential energy surfaces of this isomeric state and the ground state during the fission process, may reduce the nuclear lifetime and balance the fission stability. These results elucidate not only the enhanced stability of the high-$K$ isomeric state, including the inversion of stability between it and the ground state, but also the limitation of the stability increase of such an isomeric state.

nucl-th↗

arXiv2025

Probing the refined performance of the Categorical-Boosting algorithm to the Hartree-Fock-Bogoliubov mass model with different Skyrme forces

Nuclear mass can offer profound insights into many physical branches, e.g., nuclear physics and astrophysics, while the predicted accuracy by nuclear mass models is usually far from satisfactory until now, especially within the fully microscopic self-consistent mean-field theory. In this project, we present the predictive power for the binding energy within the the Hartree-Fock-Bogoliubov (HFB) methods with six widely used Skyrme forces (SkM*, SkP, SLy4, SV-min, UNEDF0 and UNEDF1) and evaluate the refined performance of the machine learning based on a novel Categorical Boosting (CatBoost) algorithm to the Skyrme HFB mass models. The root-mean-square (rms) deviations between the bare HFB calculations with different Skyrme forces and the available experimental data range from the minimum, about 1.43 MeV, for the UNEDF0 parameter set to the maximum, about 7.03 MeV, for the SkM* paraterer set. For the CatBoost-refined HFB predictions, the predictive power can be significantly improved. All the prediction accurancies on the testing set can reach the level around 0.2 MeV and, meanwhile, the large model bias can be reduced. The model-repair coefficients for the adopted Skyrme parameter sets are uniformly more than 80\%. Moreover, for 21 newly measured nuclei outside AME2020, the predicted masses by the CatBoost-refined HFB models are also in good agreement with the experimental data, illustrating their good generalization abilities. Intrestingly, it is found that the optimal Skyrme parameter set that possesses the highest predictive power for the bare HFB mass calculations may be not the best candidate for the CatBoost-refined HFB model, indicating the different abilities of picking up the missing ``physics'' for different Skyrme forces by the CatBoost algorithm.

nucl-th↗

arXiv2025

Probing high-order deformation effects in neutron-deficient nuclei $^{246,248}$No with improved potential-energy-surface calculations

The high-order deformation effects in even-even $^{246,248}$No are investigated by means of pairing self-consistent Woods-Saxon-Strutinsky calculations using the potential-energy-surface (PES) approach in an extended deformation space $(β_2, β_3,β_4,β_5,β_6,β_7, β_8)$. Based on the calculated two-dimensional-projected energy maps and different potential-energy curves, we find that the highly even-order deformations have an important impact on both the fission trajectory and energy minima, while the odd-order deformations, accompanying the even-order ones, primarily affect the fission path beyond the second barrier. Relative to the light actinide nuclei, nuclear ground state changes to the superdeformed configuration but the normally-deformed minimum, as the low-energy shape isomer, may still be primarily responsible for enhancing nuclear stability and ensuring experimental accessibility in $^{246,248}$No. Our present investigation indicates the nonnegligible impact of high-order deformation effects along the fission valley and will be helpful for deepening the understandings of different deformation effects and deformation couplings in nuclei, especially in this neutron-deficient heavy-mass region.

nucl-th↗

arXiv2023

Probing the structural evolution along the fission path in the superheavy nucleus $^{256}$Sg

The evolution of structure property along the fission path in the superheavy nucleus $^{256}$Sg is predicted through the multi-dimensional potential-energy(or Routhian)-surface calculations,in which the phenomenological deformed Woods-Saxon potential is adopted. Calculated nuclear deformations and fission barriers for $^{256}_{106}$Sg$_{150}$ and its neighbors, e.g., $^{258,260}$Sg, $^{254}$Rf and $^{252}$No are presented and compared with other theoretical results. A series of energy maps and curves are provided and used to evaluate the corresponding shape-instability properties, especially in the directions of triaxial $γ$ and different hexadecapole deformations (e.g., $α_{40}$, $α_{42}$ and $α_{44}$). It is found that the triaxial deformation may help the nucleus bypass the first fission-barrier of the axial case. After the first minimum in the nuclear energy surface, the fission pathway of the nucleus can be affected by $γ$ and hexadecapole deformation degrees of freedom. In addition, microscopic single-particle structure, pairing and Coriolis effects are briefly investigated and discussed.

nucl-th↗

arXiv2021

Uncertainty evaluation and correlation analysis of single-particle energies in phenomenological nuclear mean field: An investigation of propagating uncertainties for independent model parameters

Based on Monte Carlo approach and conventional error analysis theory, taking the heaviest doubly magic nucleus $^{208}$Pb as an example, we firstly evaluate the propagated uncertainties of universal potential parameters for three typical types of single-particle energies in the phenomenological Woods-Saxon mean field. Accepting the Woods-Saxon modeling with uncorrelated model parameters, we find that the standard deviations of single-particle energies obtained by the Monte Carlo simulation and the error propagation rules are in good agreement with each other. It seems that the energy uncertaintis of the single-particle levels regularly evoluate with some quantum numbers to a large extent for the given parameter uncertainties. Further, the correlation properties of the single-particle levels within the domain of input parameter uncertainties are analyzed using the method of statistical analysis, e.g., with the aid of Pearson correlation coefficients. It is found that the positive, negative or unrelated relationship may appear between two selected single-particle levels, which will be very helpful for evaluating the theoretical uncertainty related to the single-particle levels (e.g., $K$ isomer) in nuclear structural calculations.

nucl-th↗

arXiv2018

Calculation of multidimensional potential energy surfaces for even-even transuranium nuclei: Systematic investigation of the triaxiality effect on fission barrier

Static fission barriers for 95 even-even transuranium nuclei with charge number $Z=94-118$ have been systematically investigated by means of pairing self-consistent Woods-Saxon-Strutinsky calculations using the potential energy surface approach in multidimensional ($β_2$, $γ$, $β_4$) deformation space. Taking the heavier $^{252}$Cf nucleus (with the available fission barrier from experiment) as an example, the formation of the fission barrier and the influence of macroscopic, shell and pairing correction energies on it are analyzed. The results of the present calculated $β_2$ values and barrier heights are compared with previous calculations and available experiments. The role of triaxiality in the region of the first saddle is discussed. It is found that the second fission barrier is also considerably affected by the triaxial deformation degree of freedom in some nuclei (e.g., the $Z=112-118$ isotopes). Based on the potential energy curves, general trends of the evolution of the fission barrier heights and widths as a function of the nucleon numbers are investigated. In addition, the effects of Woods-Saxon potential parameter modifications (e.g., the strength of the spin-orbit coupling and the nuclear surface diffuseness) on the fission barrier are briefly discussed.

nucl-th↗

arXiv2015

High-spin level structure of the neutron-rich nucleus 91Y

High-spin level structure of the neutron-rich nucleus 91Y has been reinvestigated via the 82Se(13C, p3n)91Y reaction. A newly constructed level scheme including several key levels clarifies the uncertainties in the earlier studies. These levels are characterized by the breaking of the Z=38 and N=56 subshell closures, which involves in the spin-isospin dependent central force and tensor force.

nucl-ex↗

arXiv2014

Spin-dependent $γ$ softness or triaxiality in even-even $^{132-138}$Nd nuclei

The properties of $γ$ instability in rapidly rotating even-even $^{132-138}$Nd isotopes have been investigated using the pairing-deformation self-consistent total-Routhian-surface calculations in a deformation space of ($β_2, γ, β_4$). It is found that even-even $^{134-138}$Nd nuclei exhibit the triaxiality in both ground and excited states, even up to high-spin ones. The lightest isotope possesses a well-deformed prolate shape without $γ$ deformation component. The current numerical results are compared with previous calculations and available observables, showing basically a general agreement with the observed trend of $γ$ correlations. The existing differences between theory and experiment are analyzed and discussed briefly.

nucl-th↗