Ab Initio MCSM Calculation for Reduced Matrix Elements of E2 Operator for A=10 Nuclei

The reduced matrix elements of E2 operator for ^10Be low-lying states are evaluated with the no-core Monte Carlo shell model, which has been used to investigate the structure of light nuclei in an ab initio sense recently. The MCSM calculation converges within 20 MCSM dimensions. These MCSM results show good agreement with new experimental data and other ab initio calculations. The reduced matrix elements are investigated in terms of single-particle orbits contribution. It is found that the transition among p-shell orbits is dominant. The triaxial deformation of ^10Be, as well as its mirror nucleus ^10C, is also discussed. Meanwhile, the importance of p-shell orbits to the triaxiality is addressed.     

Shell Model Description of Neutron-Deficient Sn Isotopes

The shell model calculations in the sdgh major shell for the neutron-deficient ^106,107,108,109Sn isotopes have been carried out by using CD-Bonn and Nijmegenl two-body effective nucleon-nucleon interactions. The singleshell states and the corresponding matrix elements needed for describing Sn isotopes are reconstructed to calculate the coefficient of fractional parantage by reducing the calculation requirements. This reconstruction allows us to do the shell model calculations of the neutron deficient Sn isotopes in very reasonable time. The results are compared to the recent high-resolution experimental data and found to be in good agreement with experiments.     

Calculation of triaxial superdeformation in <Superscript>174</Superscript>Hf

A two-dimensional Total Routhian Surface (TRS) calculation with the fixed hexadecapole deformation ε4 = 0.03 was carried out for several configurations of 174Hf. Results indicate that the shell corrections have an important contribution to the formation of triaxial superdeformation in 174Hf and some possible configuration assignments are made to the 4 TSD bands experimentally found in 174Hf.     

Projected total energy surface description for axial shape asymmetry in 172W

The projected total energy surface(PTES)approach has been developed based on the triaxial projected shell model(TPSM)hybridized with the macroscopic–microscopic method.The total energy of an atomic nucleus is decomposed into macroscopic,microscopic and rotational terms.The macroscopic and microscopic components are described with the liquid drop model and Strutinsky method,respectively,and the rotational energy is given by the TPSM,the term beyond the mean field.To test theory,the PTES calculations have been carried out for the yrast states of the well deformed rare earth nucleus172W,and the theoretical results are in good agreement with the experimental data.By using the equilibrium quardrupole deformations(ε2andγ)determined by the PTES,the calculation of the transition quardrupole moment(Qt)in function of spin also reproduces the experimental data.A comparison between the PTES and TRS methods has been made for theoretical and application uses.     

Dynamical Structure of Nuclear Excitation in Continuum

Dynamical structures of collective excitation in continuum are studied by calculating the isoscalar and isovector strength as well as transition density of nuclei near the drip-line such as ^28O and ^34Ca. It is found that for some excited states in continuum the proton and neutron transition density calculated from isoscalar and isovector excitation at some given energies may be different, which will affect the calculation of the polarization for nuclei with N≠Z.     

High-K multi-particle bands and pairing reduction in 254No

The multi-particle states and rotational properties of the two-particle bands in 254No are investigated by the cranked shell model with pairing correlations treated by the particle number conserving method.The rotational bands on top of the two-particle K^π=3^+,8^− and 10^+ states and the pairing reduction are studied theoretically in 254No for the first time.The experimental excitation energies and moments of inertia of the multi-particle states are reproduced well by the calculations.Better agreement with the data is achieved by including the high-order deformation ε6,which leads to enlarged Z=100 and N=152 deformed shell gaps.An increase of J¹ in these two-particle bands compared with the ground state band is attributed to the pairing reduction due to the Pauli blocking effect.     

Sodium atom in strong magnetic fields：a pseudospectral approach

Energies and wavefunctions of low-lying states and Rydberg states for the sodium atom in uniform magnetic fields varying from 0 to 10^5T are calculated using a pseudospectral approach with a model potential in spherical coordinates. The energies are comparable with experimental results as well as those obtained by other calculations. The spectra of oscillator strength are worked out. The evolution of them with the magnetic field is shown.     

On the structure of isomeric state in neutron-rich 108Zr: A projected shell model analysis

Inspired by the recent experimental identification of the new isomer with a half-life of(620±150) ns in the very neutron-rich nucleus 108 Zr, we apply the projected shell model with axially-deformed bases to discuss possible shapes near the ground state and the nature of the isomer. The structure of the new isomer is investigated by restricting the calculation to prolate and oblate shapes. It is shown that the isomer can be understood as a K-isomer. Meanwhile, the calculation predicts more low-lying high-K configurations, which may be confirmed by future experiments.     

Rotational structure of the odd-proton nuclide 171Tm:A projected shell model study

Deformed odd-mass nuclei are ideal examples where the interplay between single-particle and collective degrees of freedom can be studied. Inspired by the recent experimental high-spin data in the odd-proton nuclide 171 Tm, we perform projected shell model(PSM) calculations to investigate structure of the ground band and other bands based on isomeric states. In addi- tion to the usual quadrupole-quadrupole force in the Hamiltonian, we employ the hexadecapole-hexadecapole(HH) interac- tion, in a self-consistent way with the hexadecapole deformation of the deformed basis. It is found that the known experi- mental data can be well described by the PSM calculation. The effect of the HH force on the quasiparticle isomeric states is discussed.     

Particle-number conserving analysis for the 2-quasiparticle and high-K multi-quasiparticle states in doubly-odd 174,176Lu

Two-quasiparticle bands and low-lying excited high-K four-, six-, and eight-quasiparticle bands in the doubly-odd 174,176 Lu are analyzed by using the cranked shell model (CSM) with the pairing correlations treated by a particle-number conserving (PNC) method, in which the blocking effects are taken into account exactly. The proton and neutron Nilsson level schemes for 174,176Lu are taken from the adjacent odd-A Lu and Hf isotopes, which are adopted to reproduce the experimental bandhead energies of the one-quasiproton and one-quasineutron bands of these odd-A Lu and Hf nuclei, respectively. Once the quasiparticle configurations are determined, the experimental bandhead energies and the moments of inertia of these two- and multi-quasiparticle bands are well reproduced by PNC-CSM calculations. The Coriolis mixing of the low-K (K=|Ω1Ω2 |) two-quasiparticle band of the Gallagher-Moszkowski doublet with one nucleon in the Ω=1/2 orbital is analyzed.     

Nucleon—Pair Shell Model：Magnetic Excitations for Ba Isotopes

Magnetic excitations for Ba isotopes are discussed within the nucleon-pair shell model truncated in the SD subspace.With the SD pair determined by a surface-δ interaction,M1 transitions for ^134Ba are well fitted.The M1 and M3 transitions for ^132Ba and ^130Ba are also predicted.It is shown that the statement,the collective magnetic properties are due to the orbital motion of nucleons,is approximately valid.     

Mixing of two-quasineutron and two-quasiproton Kπ=6+ configurations in the vicinity of 174Yb

In the framework of the projected shell model, we investigate the competition between the two-quasineutron and two-quasiproton K^π=6⁺ states in the ytterbium isotopes and N =104 isotones adjacent to ¹⁷⁴Yb. The ¹⁷⁴Yb results are compared with the experimental data.The K^π =6⁺ isomer observed in ¹⁷⁴ Yb is assigned as an admixture of the ν7/2^-[514] ν5/2^-[512] and π7/2⁺ [404]π5/2⁺ [402] intrinsic structure, which explains the experimental |g K-g R | value. Similar mixing would appear in ¹⁷⁴ Yb, ¹⁷⁶ Hf,and ¹⁷⁸ W. The low-lying K^π=6⁺ states are also predicted in ^170-178 Yb.     

Low—Lying Resonance States of Slow Electron Collisions With Atomic Oxygen

A 39-target state close-coupling calculation of low-energy electron scattering from atomic oxygen is carried out with core-valence electron correlation by using R-matrix method. It is shown that the elastic cross section has a huge and sharp increase with the electron energy going down below 1eV. This remarkable structure is attributed to a few very low-lying potential resonances and the features of these resonances are given with partial cross sections. It is also shown that after considering excitations of two electrons from 2s shell, the three lowest atomic energy levels are in agreement with experimental results better than that just considering excitations of two electrons from the 2p shell as well as only one electron from the 2s shell. Elastic and two excitation (^3P→^1D and ^3P→^1S) cross sections are given and compared with the other theoretical and experimental results.     

Nonadditivity in moments of inertia of high-K multiquasiparticle bands

The experimental high-K 2- and 3-quasiparticle bands of well deformed rare-earth nuclei are analyzed. It is found that there exists significant nonadditivity in moments of inertia (MOIs) for these bands. The microscopic mechanism of the rotational bands is investigated by the particle number conserving (PNC) method in the frame of cranked shell model with pairing, in which the blocking effects are taken care of exactly. The experimental rotational frequency dependence of these bands is well reproduced in PNC calculations. The nonadditivity in MOIs originates from the destructive interference between Pauli blocking effects.     

Ground-State Properties ,of C, O, and Ne Isotopes in Hartree——Fock-Bogoliubov Calculation with Gogny Interaction

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.     

Three-Dimensional Angular Momentum Projected Relativistic Point-Coupling Approach for Low-Lying Excited States in 24Mg

A tull three-dimensional angular momentum projection on top ot a triaxial relativistic mean-fieid calculation is implemented for the first time. The underlying Lagrangian is a point coupling model and pairing correlations are taken into account by a monopole force. This method is applied for the low-lying excited states in ^24Mg. Good agreement with the experimental data is found for the ground state properties. A minimum in the potential energy surface for the 22^＋ state, with β≈ 0.55,7 γ≈ 10^o, is used as the basis to investigate the rotational energy spectrum as well as the corresponding B（E2） transition probabilities as compared to the available data.     

Triaxiality of High-K Isomers in A~130 Region

Remarkable triaxiality is found in the high-K isomeric states of A-130 nuclei using the configuration-constrained calculations of potential-energy surfaces. The triaxiality gives the further understanding of the decay properties of the isomers. The calculation with triaxiality can well explain the measured quadrupole moment of the K^z=7^- isomer in ^130Ce.