The beyond-dripline oxygen isotopes^(27,28)O were recently observed at RIKEN,and were found to be unbound decaying into^(24)O by emitting neutrons.The unbound feature of the heaviest oxygen isotope,^(28)O,provides an ...The beyond-dripline oxygen isotopes^(27,28)O were recently observed at RIKEN,and were found to be unbound decaying into^(24)O by emitting neutrons.The unbound feature of the heaviest oxygen isotope,^(28)O,provides an excellent test for stateof-the-art nuclear models.The atomic nucleus is a self-organized quantum manybody system comprising specific numbers of protons Z and neutrons N.展开更多
High multipole electromagnetic transitions are rare in nature.The highest-multipole transition observed in atomic nuclei is the electric hexacontatetrapole E6 transition from the T_(1/2)=2.54(2)-min J^(π)=1_(9/2)-iso...High multipole electromagnetic transitions are rare in nature.The highest-multipole transition observed in atomic nuclei is the electric hexacontatetrapole E6 transition from the T_(1/2)=2.54(2)-min J^(π)=1_(9/2)-isomer to the 7/2^(-)ground state in^(53)Fe with an angular momentum change of six units.In the present work,we performed ab initio calculations for this unique case by employing chiral effective field theory(EFT)forces.The in-medium similarity renormalization group is used to derive the valence-space effective Hamiltonian and multipolar transition operators.Bare nucleon charges were used in all the multipolar transition rate calculations,providing good agreement with the experimental data.The valence space takes the full fp shell.In^(53)Fe,the low-lying states were dominated by the 0f_(7/2)component.Two different versions of the chiral EFT two-plus three-nucleon interaction were used to test the dependence on the interaction used.We also tested the convergence of the transition rate calculations against the harmonic oscillator parameter hΩand basis truncations e_(max)and E_(3max)for twoand three-nucleon forces,respectively.展开更多
The full configuration interaction quantum Monte Carlo(FCIQMC)method,originally developed in quantum chemistry,has also been successful for both molecular and condensed matter systems.Another natural extension of this...The full configuration interaction quantum Monte Carlo(FCIQMC)method,originally developed in quantum chemistry,has also been successful for both molecular and condensed matter systems.Another natural extension of this methodology is its application to nuclear structure calculations.We developed an FCIQMC approach to study nuclear systems.To validate this method,we applied FCIQMC to a small model space,where the standard shell model remains computationally feasible.Specifically,we performed calculations for?ωisotopes using pf-shell GXPF1A interaction and compared the results with those obtained from the standard shell model calculations.To further demonstrate the capabilities of the FCIQMC,we investigated its performance in systems exhibiting strong correlations,where conventional nuclear structure models are less effective.Using an artificially constructed strongly correlated system with a modified GXPF1A interaction,our calculations revealed that FCIQMC delivered superior results compared to many existing methods.Finally,we applied FCIQMC to Fe isotopes in the sdpf-shell model space,showing its potential to perform accurate calculations in large model spaces that are inaccessible to the shell model because of the limitations of current computational resources.展开更多
Starting from the CD-Bonn potential, we have performed Gamow shell-model calculations for neutronrich oxygen isotopes, investigating excitation spectra and their resonant properties. The Gamow shell model is based on ...Starting from the CD-Bonn potential, we have performed Gamow shell-model calculations for neutronrich oxygen isotopes, investigating excitation spectra and their resonant properties. The Gamow shell model is based on the Berggren ensemble, which is capable of treating the continuum effect reasonably in weakly bound or unbound nuclei. To calculate heavier-mass oxygen isotopes, we choose ^16O as a frozen core in the Camow shell-model calculations. The first 2^＋ excitation energies of the even-even O isotopes are calculated, and compared with those obtained by the conventional shell model using the empirical USDB interaction. The continuum effect is proved to play an important role in the shell evolution near the drip line. We also discuss the effect of the Berggren contour choice. We improve the approximation in the contour choice to give more precise calculations of resonance widths.展开更多
The collective rotations of the K^π=5^- configuration in neutron-rich Mo, Ru and Pd isotopes were systematically investigated by the configuration-constrained cranking shell model based on the Skyrme Hartree-Fock met...The collective rotations of the K^π=5^- configuration in neutron-rich Mo, Ru and Pd isotopes were systematically investigated by the configuration-constrained cranking shell model based on the Skyrme Hartree-Fock method with pairing treated by shell-model diagonalization. The calculations efficiently reproduce the experimental moments of inertia of both the ground-state and side bands. Rotational bands built on two-particle K^π=5^- configurations have been the subject of intense study. Possible configurations were assigned to the observed 5^- bands in ^102-106Mo,^108-112Ru and ^112-114Pd. We predict the existence of the 5^- bands in ^108,110Mo. These results provide deep insights into the structure of neutron-rich nuclei, and provide useful information for future experiments.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.12335007,11835001,11921006,12035001 and 12205340)the State Key Laboratory of Nuclear Physics and Technology,Peking University(No.NPT2020KFY13)Gansu Natural Science Foundation(No.22JR5RA123).
文摘The beyond-dripline oxygen isotopes^(27,28)O were recently observed at RIKEN,and were found to be unbound decaying into^(24)O by emitting neutrons.The unbound feature of the heaviest oxygen isotope,^(28)O,provides an excellent test for stateof-the-art nuclear models.The atomic nucleus is a self-organized quantum manybody system comprising specific numbers of protons Z and neutrons N.
基金supported by the National Key R&D Program of China(Nos.2024YFA1610900 and 2023YFA1606401)the National Natural Science Foundation of China(Nos.12335007 and 12035001)the United Kingdom Science and Technology Facilities Council(No.ST/V001108/1)。
文摘High multipole electromagnetic transitions are rare in nature.The highest-multipole transition observed in atomic nuclei is the electric hexacontatetrapole E6 transition from the T_(1/2)=2.54(2)-min J^(π)=1_(9/2)-isomer to the 7/2^(-)ground state in^(53)Fe with an angular momentum change of six units.In the present work,we performed ab initio calculations for this unique case by employing chiral effective field theory(EFT)forces.The in-medium similarity renormalization group is used to derive the valence-space effective Hamiltonian and multipolar transition operators.Bare nucleon charges were used in all the multipolar transition rate calculations,providing good agreement with the experimental data.The valence space takes the full fp shell.In^(53)Fe,the low-lying states were dominated by the 0f_(7/2)component.Two different versions of the chiral EFT two-plus three-nucleon interaction were used to test the dependence on the interaction used.We also tested the convergence of the transition rate calculations against the harmonic oscillator parameter hΩand basis truncations e_(max)and E_(3max)for twoand three-nucleon forces,respectively.
基金supported by the National Key R&D Program of China(Nos.2024YFA1610900,2023YFA1606401,and 2023YFA1606403)the National Natural Science Foundation of China(Nos.12335007,12035001 and 12205340)。
文摘The full configuration interaction quantum Monte Carlo(FCIQMC)method,originally developed in quantum chemistry,has also been successful for both molecular and condensed matter systems.Another natural extension of this methodology is its application to nuclear structure calculations.We developed an FCIQMC approach to study nuclear systems.To validate this method,we applied FCIQMC to a small model space,where the standard shell model remains computationally feasible.Specifically,we performed calculations for?ωisotopes using pf-shell GXPF1A interaction and compared the results with those obtained from the standard shell model calculations.To further demonstrate the capabilities of the FCIQMC,we investigated its performance in systems exhibiting strong correlations,where conventional nuclear structure models are less effective.Using an artificially constructed strongly correlated system with a modified GXPF1A interaction,our calculations revealed that FCIQMC delivered superior results compared to many existing methods.Finally,we applied FCIQMC to Fe isotopes in the sdpf-shell model space,showing its potential to perform accurate calculations in large model spaces that are inaccessible to the shell model because of the limitations of current computational resources.
基金Supported by the National Key R&D Program of China(2018YFA0404401)the National Natural Science Foundation of China(11320101004,11575007)+2 种基金the China Postdoctoral Science Foundation(2018M630018)the CUSTIPEN(China U.S.Theory Institute for Physics with Exotic Nuclei)funded by the U.S.Department of Energy,Office of Science(DESC0009971)and High performance Computing Platform of Peking University
文摘Starting from the CD-Bonn potential, we have performed Gamow shell-model calculations for neutronrich oxygen isotopes, investigating excitation spectra and their resonant properties. The Gamow shell model is based on the Berggren ensemble, which is capable of treating the continuum effect reasonably in weakly bound or unbound nuclei. To calculate heavier-mass oxygen isotopes, we choose ^16O as a frozen core in the Camow shell-model calculations. The first 2^＋ excitation energies of the even-even O isotopes are calculated, and compared with those obtained by the conventional shell model using the empirical USDB interaction. The continuum effect is proved to play an important role in the shell evolution near the drip line. We also discuss the effect of the Berggren contour choice. We improve the approximation in the contour choice to give more precise calculations of resonance widths.
基金Supported by the National Key R&D Program of China(2018YFA0404401)the National Natural Science Foundation of China(11835001,11575007,11847203)the China Postdoctoral Science Foundation(2018M630018)
文摘The collective rotations of the K^π=5^- configuration in neutron-rich Mo, Ru and Pd isotopes were systematically investigated by the configuration-constrained cranking shell model based on the Skyrme Hartree-Fock method with pairing treated by shell-model diagonalization. The calculations efficiently reproduce the experimental moments of inertia of both the ground-state and side bands. Rotational bands built on two-particle K^π=5^- configurations have been the subject of intense study. Possible configurations were assigned to the observed 5^- bands in ^102-106Mo,^108-112Ru and ^112-114Pd. We predict the existence of the 5^- bands in ^108,110Mo. These results provide deep insights into the structure of neutron-rich nuclei, and provide useful information for future experiments.
