The damping and frequency-shift in Landau mechanism of a quadrupole mode in a disc-shaped rubidium Bose-Einstein condensate are investigated by using the Hartree-Fock-Bogoliubov approximation. The practical relaxation...The damping and frequency-shift in Landau mechanism of a quadrupole mode in a disc-shaped rubidium Bose-Einstein condensate are investigated by using the Hartree-Fock-Bogoliubov approximation. The practical relaxations of the elementary excitations and the orthometric relation among them are taken into account to obtain advisable calculation formula for damping as well as frequency-shift. The first approximation of Gaussian distribution function is employed for the ground-state wavefunction to suitably eliminate the divergence of the analytic three-mode coupling matrix elements. According to these methods, both Landau damping rate and frequency-shift of the quadrupole mode are analytically calculated. In addition, all the theoretical results agree with the experimental ones.展开更多
The possible exotic nuclear properties in the neutron-rich Ca,Ni,Zr,and Sn isotopes are examined with the continuum Skyrme Hartree-Fock-Bogoliubov theory in the framework of the Green’s function method.The pairing co...The possible exotic nuclear properties in the neutron-rich Ca,Ni,Zr,and Sn isotopes are examined with the continuum Skyrme Hartree-Fock-Bogoliubov theory in the framework of the Green’s function method.The pairing correlation,the couplings with the continuum,and the blocking effects for the unpaired nucleon in odd-A nuclei are properly treated.The Skyrme interaction SLy4 is adopted for the ph channel and the density-dependentinteraction is adopted for the pp chan-nel,which well reproduce the experimental two-neutron separation energies S_(2n)and one-neutron separation energies Sn.It is found that the criterion S_(n)>0 predicts a neutron drip line with neutron numbers much smaller than those for S_(2n)>0.Owing to the unpaired odd neutron,the neutron pairing energies−E_(pair)in odd-A nuclei are much lower than those in the neighbor-ing even-even nuclei.By investigating the single-particle structures,the possible halo structures in the neutron-rich Ca,Ni,and Sn isotopes are predicted,where sharp increases in the root-mean-square(rms)radii with significant deviations from the traditional rA^(1∕3)rule and diffuse spatial density distributions are observed.Analyzing the contributions of various partial waves to the total neutron densityρlj(r)∕ρ(r)reveals that the orbitals located around the Fermi surface-particularly those with small angular momenta-significantly affect the extended nuclear density and large rms radii.The number of neutrons Nλ(N_(0))occupying above the Fermi surfacen(continuum threshold)is discussed,whose evolution as a function of the mass number A in each isotope is consistent with that of the pairing energy,supporting the key role of the pairing correlation in halo phenomena.展开更多
We investigate the Landau damping of the collective mode in a quasi-one-dimensional repulsive Bose-Einstein condensate by using the self-consistent time-dependent Hartree-Fock-Bogoliubov approximation.We put forward a...We investigate the Landau damping of the collective mode in a quasi-one-dimensional repulsive Bose-Einstein condensate by using the self-consistent time-dependent Hartree-Fock-Bogoliubov approximation.We put forward a new method to calculate the Landau damping rate of the collective mode in the condensate and discuss the dependence of the Landau damping on temperature,on transverse trapping frequency,on atom number in the condensate,and on length of the system.Different from the usual calculation method for the three dimension system,our new calculation method is an interactive one by considering the practical relaxation of the elementary excitation.With little approximation,our theoretical calculation results agree with the experimental ones.Comparing with the usual calculation method,our theory is helpful to deduce the inter-particle interactions in damping phenomenon.展开更多
In this work, the effects of the pairing correlation on the properties of neutron drops N=6-50 trapped in a harmonic oscillator potential with ω = 10 Me V are investigated by comparing the results given by the Skyrme...In this work, the effects of the pairing correlation on the properties of neutron drops N=6-50 trapped in a harmonic oscillator potential with ω = 10 Me V are investigated by comparing the results given by the Skyrme Hartree-Fock and Hartree-FockBogoliubov theories with the density-dependent delta interaction(DDDI) pairing force. The results showed that the pairing correlation slightly made the neutron drops more bound, and increased the central neutron density, the spin-orbit and pseudo spin-orbit splittings. Thus, the pairing correlation must be accounted for to improve the Skyrme functional compared with the ab initio calculations. Furthermore, although the single-particle energy gaps with or without pairing were similar, the shell closures varied due to pair scattering. Here, the shell closures in neutron drops using the Sk M* parameter set and DDDI pairing force were found at N=8, 16, and 32.展开更多
The quasiparticle resonances are investigated by examining three kinds of quasiparticle spectra, i.e., the density of quasiparticle states, the occupation number density, and the pair number density in the continuum S...The quasiparticle resonances are investigated by examining three kinds of quasiparticle spectra, i.e., the density of quasiparticle states, the occupation number density, and the pair number density in the continuum Skyrme Hartree-Fock-Bogoliubov theory with the Green’s function method. Taking the weakly bound nucleus 66Ca as an example, the quasiparticle resonant energies and widths extracted from these three kinds of quasiparticle spectra are compared. For the narrow resonances, the extracted resonant energy and the width are consistent with each other. However, it is difficult to use the density of quasiparticle states to identify the broad resonances due to the background of nonresonant continuum. By switching off the pairing potential and/or the Hartree-Fock(HF) potential respectively in the calculation of these quasiparticle spectra, the roles of HF mean-field and pairing correlations in the quasiparticle resonances are demonstrated clearly. It turns out that all the quasiparticle resonances corresponding to the deeply bound, weakly bound and positive-energy single-particle resonant states, are mainly contributed by the HF potential. The pairing potential helps to slightly increase the resonant energy and the width. However, the pairing potential is important to make the nucleons occupy the low-lying nonresonant continuum states near the threshold and take part in the pairing correlations here,especially for the partial waves with small angular momentum ?.展开更多
The coordinate-space Hartree-Fock-Bogoliubov（HFB） approach with quasiparticle blocking has been applied to study the odd-A weakly bound nuclei ^17,19B and ^37Mg,in which halo structures have been reported in experim...The coordinate-space Hartree-Fock-Bogoliubov（HFB） approach with quasiparticle blocking has been applied to study the odd-A weakly bound nuclei ^17,19B and ^37Mg,in which halo structures have been reported in experiments.The Skyrme nuclear forces SLy4 and UNEDF1 have been adopted in our calculations.The results with and without blocking have been compared to demonstrate the emergence of deformed halo structures due to blocking effects.In our calculations,^19B and ^37Mg have remarkable features of deformed halos.展开更多
We study the collapse dynamics of a Bose-Einstein condensate subjected to a sudden change of the scattering length to a negative value by adopting the self-consistent Gaussian state theory for mixed states.Compared to...We study the collapse dynamics of a Bose-Einstein condensate subjected to a sudden change of the scattering length to a negative value by adopting the self-consistent Gaussian state theory for mixed states.Compared to the Gross-Pitaevskii and the Hartree-Fock-Bogoliubov approaches,both fluctuations and three-body loss are properly treated in our theory.We find a new type of collapse assisted by fluctuations that amplify the attractive interaction between atoms.Moreover,the calculation of the fluctuated atoms,the entropy,and the second-order correlation function showed that the collapsed gas significantly deviated from a pure state.展开更多
The tensor force and pairing correlation effects on the two-proton radioactivity of^(18)Mg and^(20)Si with a pronounced two-proton halo are explored in the framework of spherical Skyrme-Hartree-Fock-Bogoliubov theory....The tensor force and pairing correlation effects on the two-proton radioactivity of^(18)Mg and^(20)Si with a pronounced two-proton halo are explored in the framework of spherical Skyrme-Hartree-Fock-Bogoliubov theory.It is shown that the halo sizes are enhanced with the increase in the strength of the tensor force and pairing correlation.Furthermore,the increasing halo sizes lead to the enhancement of diproton emission.Then,the tensor force is found to have a small influence on the two-proton decay energies,and the two-proton decay energies calculated with strong surface pairing are smaller than those with weak mixed pairing.Because the two-proton decay energies are relat-ively large,the predicted order of magnitude of half-lives within the effective liquid drop model is not sensitive to the decay energy variation caused by the tensor force and pairing correlation,which has a value of approximately 10^(-18)s.展开更多
基于Gogny核子-核子有效相互作用,发展了适用于描写原子核裂变过程、不包含任何对称性限制以及三维时间相关的Hartree-Fock-Bogoliubov理论计算程序(Gogny-TDHFB Code for Fission).程序包含静态裂变势能面计算的多维度集体自由度约束HF...基于Gogny核子-核子有效相互作用,发展了适用于描写原子核裂变过程、不包含任何对称性限制以及三维时间相关的Hartree-Fock-Bogoliubov理论计算程序(Gogny-TDHFB Code for Fission).程序包含静态裂变势能面计算的多维度集体自由度约束HFB和裂变动力学计算的TDHFB两部分.在(x,y)方向采用形变谐振子基.在z方向上,为了描述裂变直至断点和断后的极端形变,采用Lagrange mesh方法.利用本程序,对240Pu的裂变势能路径和断点动力学过程进行了计算.结果表明,240Pu存在对称和非对称两条裂变路径;三轴形变可以显著降低第一(内)裂变位垒;对能在断裂过程中起着重要作用.展开更多
The two-neutron separation energies(S2n)andα-decay energies(Qα)of the Z=114 isotopes are calculated by the deformed Skyrme-Hartree-Fock-Bogoliubov(SHFB)approach with the SLy5,T22,T32 and T43 interactions.It is found...The two-neutron separation energies(S2n)andα-decay energies(Qα)of the Z=114 isotopes are calculated by the deformed Skyrme-Hartree-Fock-Bogoliubov(SHFB)approach with the SLy5,T22,T32 and T43 interactions.It is found that the tensor force effect on the bulk properties is weak and the shell closure at N=184 is seen evidently with these interactions by analyzing the S2n and Qαevolutions with neutron number N.Meanwhile,the single-particle energy spectra of 298114 are studied using the spherical SHFB approach with these interactions to furthermore examine the shell structure of the magic nucleus 298114.It is shown that the shell structure is almost not changed by the inclusion of the tensor force in the Skyrme interactions.Finally,by examining the energy splitting of the three pairs of pseudospin partners for the protons and neutrons of 298114,it is concluded that the pseudospin symmetry of the neutron states is preserved better than that of the proton states and not all of the pseudospin symmetries of the proton and neutron states are influenced by the tensor force.展开更多
Ground-state properties of C, O, and Ne isotopes are described in the framework of Hartree-Fock-Bogoliubov theory with density-dependent finite-range Gogny interaction D1S. We include all the contributions to the Hart...Ground-state properties of C, O, and Ne isotopes are described in the framework of Hartree-Fock-Bogoliubov theory with density-dependent finite-range Gogny interaction D1S. We include all the contributions to the Hartree-Fock and pairing feld arising from Gogny and Coulomb interaction as well as the center of mass correction in the numerical calcu/ations. These ground-state properties of C, O, and Ne isotopes are compared with available experimental results, Hartree-Fock plus BCS, shell model and relativistic Hartree--Bogoliubov calculations. The agreement between experiments and our theoretical results is pretty well. The predicted drip-line is dependent strongly on the model and effective interaction due to their sensitivity to various theoretical details. The calculations predict no evidence for halo structure predicted for C,O, and Ne isotopes in a previous RHB study.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11264039)the Key Discipline of Theoretical Physics of Xinjiang,China(Grant Nos.LLWLY201202 and LLWLY201203)the Postgraduate Scientific and Theoretical Innovation Project of Xinjiang Normal University,China(Grant No.20131234)
文摘The damping and frequency-shift in Landau mechanism of a quadrupole mode in a disc-shaped rubidium Bose-Einstein condensate are investigated by using the Hartree-Fock-Bogoliubov approximation. The practical relaxations of the elementary excitations and the orthometric relation among them are taken into account to obtain advisable calculation formula for damping as well as frequency-shift. The first approximation of Gaussian distribution function is employed for the ground-state wavefunction to suitably eliminate the divergence of the analytic three-mode coupling matrix elements. According to these methods, both Landau damping rate and frequency-shift of the quadrupole mode are analytically calculated. In addition, all the theoretical results agree with the experimental ones.
基金the National Natural Science Foundation of China(No.U2032141)the Open Project of Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology(No.NLK2022-02)+4 种基金the Central Government Guidance Funds for Local Scientific and Technological Development,China(Guike ZY22096024)the Natural Science Foundation of Henan Province(No.202300410479)the Guizhou Provincial Science and Technology Projects(No.ZK[2022]203)the Foundation of Fundamental Research for Young Teachers of Zhengzhou University(No.JC202041041)the Physics Research and Development Program of Zhengzhou University(No.32410217).
文摘The possible exotic nuclear properties in the neutron-rich Ca,Ni,Zr,and Sn isotopes are examined with the continuum Skyrme Hartree-Fock-Bogoliubov theory in the framework of the Green’s function method.The pairing correlation,the couplings with the continuum,and the blocking effects for the unpaired nucleon in odd-A nuclei are properly treated.The Skyrme interaction SLy4 is adopted for the ph channel and the density-dependentinteraction is adopted for the pp chan-nel,which well reproduce the experimental two-neutron separation energies S_(2n)and one-neutron separation energies Sn.It is found that the criterion S_(n)>0 predicts a neutron drip line with neutron numbers much smaller than those for S_(2n)>0.Owing to the unpaired odd neutron,the neutron pairing energies−E_(pair)in odd-A nuclei are much lower than those in the neighbor-ing even-even nuclei.By investigating the single-particle structures,the possible halo structures in the neutron-rich Ca,Ni,and Sn isotopes are predicted,where sharp increases in the root-mean-square(rms)radii with significant deviations from the traditional rA^(1∕3)rule and diffuse spatial density distributions are observed.Analyzing the contributions of various partial waves to the total neutron densityρlj(r)∕ρ(r)reveals that the orbitals located around the Fermi surface-particularly those with small angular momenta-significantly affect the extended nuclear density and large rms radii.The number of neutrons Nλ(N_(0))occupying above the Fermi surfacen(continuum threshold)is discussed,whose evolution as a function of the mass number A in each isotope is consistent with that of the pairing energy,supporting the key role of the pairing correlation in halo phenomena.
基金Supported by National Natural Science Foundation of China under Grant No.10864006the Key Research Project of Xinjiang Higher Education,China under Grant No.XJED2010141the Key Discipline of Theoretical Physics of Xinjiang,China and the Postgraduate Scientific and Technological Innovation Project of Xinjiang Normal University,China under Grant No.20111202
文摘We investigate the Landau damping of the collective mode in a quasi-one-dimensional repulsive Bose-Einstein condensate by using the self-consistent time-dependent Hartree-Fock-Bogoliubov approximation.We put forward a new method to calculate the Landau damping rate of the collective mode in the condensate and discuss the dependence of the Landau damping on temperature,on transverse trapping frequency,on atom number in the condensate,and on length of the system.Different from the usual calculation method for the three dimension system,our new calculation method is an interactive one by considering the practical relaxation of the elementary excitation.With little approximation,our theoretical calculation results agree with the experimental ones.Comparing with the usual calculation method,our theory is helpful to deduce the inter-particle interactions in damping phenomenon.
基金the National Natural Science Foundation of China(Grant Nos.11405116,and 11775119).
文摘In this work, the effects of the pairing correlation on the properties of neutron drops N=6-50 trapped in a harmonic oscillator potential with ω = 10 Me V are investigated by comparing the results given by the Skyrme Hartree-Fock and Hartree-FockBogoliubov theories with the density-dependent delta interaction(DDDI) pairing force. The results showed that the pairing correlation slightly made the neutron drops more bound, and increased the central neutron density, the spin-orbit and pseudo spin-orbit splittings. Thus, the pairing correlation must be accounted for to improve the Skyrme functional compared with the ab initio calculations. Furthermore, although the single-particle energy gaps with or without pairing were similar, the shell closures varied due to pair scattering. Here, the shell closures in neutron drops using the Sk M* parameter set and DDDI pairing force were found at N=8, 16, and 32.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0404400)the National Natural Science Foundation of China(Grant Nos.11621131001,11405116,and 11875075)
文摘The quasiparticle resonances are investigated by examining three kinds of quasiparticle spectra, i.e., the density of quasiparticle states, the occupation number density, and the pair number density in the continuum Skyrme Hartree-Fock-Bogoliubov theory with the Green’s function method. Taking the weakly bound nucleus 66Ca as an example, the quasiparticle resonant energies and widths extracted from these three kinds of quasiparticle spectra are compared. For the narrow resonances, the extracted resonant energy and the width are consistent with each other. However, it is difficult to use the density of quasiparticle states to identify the broad resonances due to the background of nonresonant continuum. By switching off the pairing potential and/or the Hartree-Fock(HF) potential respectively in the calculation of these quasiparticle spectra, the roles of HF mean-field and pairing correlations in the quasiparticle resonances are demonstrated clearly. It turns out that all the quasiparticle resonances corresponding to the deeply bound, weakly bound and positive-energy single-particle resonant states, are mainly contributed by the HF potential. The pairing potential helps to slightly increase the resonant energy and the width. However, the pairing potential is important to make the nucleons occupy the low-lying nonresonant continuum states near the threshold and take part in the pairing correlations here,especially for the partial waves with small angular momentum ?.
基金Supported by National Key Basic Research Program of China(2013CB83440)National Natural Science Foundation of China(11375016,11235001,11320101004)Research Fund for Doctoral Program of Higher Education of China(20130001110001)
文摘The coordinate-space Hartree-Fock-Bogoliubov（HFB） approach with quasiparticle blocking has been applied to study the odd-A weakly bound nuclei ^17,19B and ^37Mg,in which halo structures have been reported in experiments.The Skyrme nuclear forces SLy4 and UNEDF1 have been adopted in our calculations.The results with and without blocking have been compared to demonstrate the emergence of deformed halo structures due to blocking effects.In our calculations,^19B and ^37Mg have remarkable features of deformed halos.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA0718304)the NSFC(Grants No.12135018 and No.12047503)the Strategic Priority Research Program of CAS(Grant No.XDB28000000)
文摘We study the collapse dynamics of a Bose-Einstein condensate subjected to a sudden change of the scattering length to a negative value by adopting the self-consistent Gaussian state theory for mixed states.Compared to the Gross-Pitaevskii and the Hartree-Fock-Bogoliubov approaches,both fluctuations and three-body loss are properly treated in our theory.We find a new type of collapse assisted by fluctuations that amplify the attractive interaction between atoms.Moreover,the calculation of the fluctuated atoms,the entropy,and the second-order correlation function showed that the collapsed gas significantly deviated from a pure state.
基金Supported by the National Natural Science Foundation of China(U1832120,11675265)the Natural Science Foundation for Outstanding Young Scholars of Hebei Province,China(A2020210012)+4 种基金the Natural Science Foundation of Hebei Province,China(A2021210010)the Key Laboratory of High Precision Nuclear Spectroscopy,Institute of Modern Physics,Chinese Academy of Sciences(IMPKFKT2021002)the Graduate Student Innovative Research Project of Shijiazhuang Tiedao University(YC2022062)the Continuous Basic Scientific Research Project(WDJC-2019-13)the Leading Innovation Project(LC 192209000701).
文摘The tensor force and pairing correlation effects on the two-proton radioactivity of^(18)Mg and^(20)Si with a pronounced two-proton halo are explored in the framework of spherical Skyrme-Hartree-Fock-Bogoliubov theory.It is shown that the halo sizes are enhanced with the increase in the strength of the tensor force and pairing correlation.Furthermore,the increasing halo sizes lead to the enhancement of diproton emission.Then,the tensor force is found to have a small influence on the two-proton decay energies,and the two-proton decay energies calculated with strong surface pairing are smaller than those with weak mixed pairing.Because the two-proton decay energies are relat-ively large,the predicted order of magnitude of half-lives within the effective liquid drop model is not sensitive to the decay energy variation caused by the tensor force and pairing correlation,which has a value of approximately 10^(-18)s.
文摘基于Gogny核子-核子有效相互作用,发展了适用于描写原子核裂变过程、不包含任何对称性限制以及三维时间相关的Hartree-Fock-Bogoliubov理论计算程序(Gogny-TDHFB Code for Fission).程序包含静态裂变势能面计算的多维度集体自由度约束HFB和裂变动力学计算的TDHFB两部分.在(x,y)方向采用形变谐振子基.在z方向上,为了描述裂变直至断点和断后的极端形变,采用Lagrange mesh方法.利用本程序,对240Pu的裂变势能路径和断点动力学过程进行了计算.结果表明,240Pu存在对称和非对称两条裂变路径;三轴形变可以显著降低第一(内)裂变位垒;对能在断裂过程中起着重要作用.
基金supported by the National Natural Science Foundation of China(Grants No.U1832120 and No.11675265)the Natural Science Foundation for Outstanding Young Scholars of Hebei Province of China(Grant No.A2018210146)the Continuous Basic Scientific Research Project(Grant No.WDJC-2019-13).
文摘The two-neutron separation energies(S2n)andα-decay energies(Qα)of the Z=114 isotopes are calculated by the deformed Skyrme-Hartree-Fock-Bogoliubov(SHFB)approach with the SLy5,T22,T32 and T43 interactions.It is found that the tensor force effect on the bulk properties is weak and the shell closure at N=184 is seen evidently with these interactions by analyzing the S2n and Qαevolutions with neutron number N.Meanwhile,the single-particle energy spectra of 298114 are studied using the spherical SHFB approach with these interactions to furthermore examine the shell structure of the magic nucleus 298114.It is shown that the shell structure is almost not changed by the inclusion of the tensor force in the Skyrme interactions.Finally,by examining the energy splitting of the three pairs of pseudospin partners for the protons and neutrons of 298114,it is concluded that the pseudospin symmetry of the neutron states is preserved better than that of the proton states and not all of the pseudospin symmetries of the proton and neutron states are influenced by the tensor force.
文摘Ground-state properties of C, O, and Ne isotopes are described in the framework of Hartree-Fock-Bogoliubov theory with density-dependent finite-range Gogny interaction D1S. We include all the contributions to the Hartree-Fock and pairing feld arising from Gogny and Coulomb interaction as well as the center of mass correction in the numerical calcu/ations. These ground-state properties of C, O, and Ne isotopes are compared with available experimental results, Hartree-Fock plus BCS, shell model and relativistic Hartree--Bogoliubov calculations. The agreement between experiments and our theoretical results is pretty well. The predicted drip-line is dependent strongly on the model and effective interaction due to their sensitivity to various theoretical details. The calculations predict no evidence for halo structure predicted for C,O, and Ne isotopes in a previous RHB study.
