Shape evolution of ~(72,74)Kr with temperature in covariant density functional theory

The rich phenomena of deformations in neutron-deficient krypton isotopes,such as shape evolution with neutron number and shape coexistence,have attracted the interest of nuclear physicists for decades.It is interesting to study such shape phenomena using a novel way,e.g.by thermally exciting the nucleus.In this work,we develop the finite temperature covariant density functional theory for axially deformed nuclei with the treatment of pairing correlations by the BCS approach,and apply this approach for the study of shape evolution in ~(72,74)Kr with increasing temperature.For ~(72)Kr,with temperature increasing,the nucleus firstly experiences a relatively quick weakening in oblate deformation at temperature T~0.9 Me V,and then changes from oblate to spherical at T~2.1 Me V.For ~(74)Kr,its global minimum is at quadrupole deformation β_2~-0.14 and abruptly changes to spherical at T~1.7 MeV.The proton pairing transition occurs at critical temperature 0.6 MeV following the rule Tc =0.6?p(0),where ?p(0) is the proton pairing gap at zero temperature.The signatures of the above pairing transition and shape changes can be found in the specific heat curve.The single-particle level evolutions with temperature are presented.     

Screening effects on ~(12)C+~(12)C fusion reaction

One of the important reactions for nucleosynthesis in the carbon burning phase in high-mass stars is the ~(12)C+~(12)C fusion reaction. In this study, we investigate the influences of the nuclear potentials and screening effect on astrophysically interesting ~(12)C+~(12)C fusion reaction observables at sub-barrier energies by using the microscopic α-αdouble folding cluster(DFC) potential and the proximity potential. In order to model the screening effects on the experimental data, a more general exponential cosine screened Coulomb(MGECSC) potential including Debye and quantum plasma cases has been considered in the calculations for the ~(12)C+~(12)C fusion reaction. In the calculations of the reaction observables, the semi-classical Wentzel-Kramers-Brillouin(WKB) approach and coupled channel(CC)formalism have been used. Moreover, in order to investigate how the potentials between ~(12)C nuclei produce molecular cluster states of ~(24)Mg, the normalized resonant energy states of ~(24)Mg cluster bands have been calculated for the DFC potential. By analyzing the results produced from the fusion of ~(12)C+~(12)C, it is found that taking into account the screening effects in terms of MGECSC is important for explaining the ~(12)C+~(12)C fusion data, and the microscopic DFC potential is better than the proximity potential in explaining the experimental data, also considering that clustering is dominant for the structure of the ~(24)Mg nucleus.     

Angular distribution measurement for ~(12)C fragmentation via ~(12)C + ~(12)C scattering at 100 MeV/u

The angular distributions and energy spectra of~(11)B,~(10)B,and~9Be fragments of~(12)C in the angular range from 1.0°~to 7.5°~at 100 Me V/u were obtained via~(12)C+~(12)C scattering.Detailed comparisons are presented between the experimental data and the modified antisymmetrized molecular dynamics(AMD-FM),binary intranuclear cascade model(BIC)and Liege intranuclear cascade model(INCL++).The experimental angular distributions and energy spectra are well reproduced by the AMD-FM calculations but fail to be reproduced by the physical models installed in the Geant4 program,including the BIC and INCL++models.     

Magnetic moments of odd-A aluminum isotopes in covariant density functional theory

The ground-state properties, especially the magnetic moments, of odd-A aluminum isotopes have been studied and well reproduced in covariant density functional theory after considering the rotational coupling. The present calculations support the rotational structure in the ground state of odd-A aluminum isotopes, i.e. the ground state 5/2~+ is built on the intrinsic state 5/2[202]. In addition, the contribution from the time-odd fields is also discussed.     

水分子链受限于单壁碳纳米管结构的密度泛函理论研究

本文采用第一性原理的密度泛函理论,主要以(6,6)Armchair型,(11,0)Zigzag型单壁碳纳米管为研究对象,研究了水分子链在碳纳米管内部吸附的稳定结构,以及结合能随其结构的变化.结果表明:当水分子链受限于碳纳米管内部时,引起碳纳米管直径收缩,这主要是由于水分子链与碳纳米管之间的氢键作用以及范德华弱相互作用所引起的.随着碳纳米管半径的增加,两种单体之间的结合能逐渐减小,但当碳纳米管半径增加至6.78时,其结合能又有所增加,这是由于在优化过程中,水分子链单体之间的氢键作用大于水分子链与碳纳米管之 关键词： 水分子链/单壁碳纳米管 密度泛函理论 结构稳定性     

A 3D non-local density functional theory for any pore geometry

A general framework of classical non-local density functional theory (NLDFT) is presented, in order to consider the adsorption of spherical molecules in porous materials of any geometry. Fluid-fluid interactions and fluid-solid interactions can be repulsive or attractive. Some techniques that have been developed for the computation of weighted densities of hard-spheres are extended to attractive ones, in order to deal with an arbitrary pore geometry. This way, the computation method introduced in this work is validated by a comparison with analytical results for simple cases, and is directly applied to more complex systems. Density distributions depending on multi-dimensional effects are presented, and some radial distribution functions are recovered from NLDFT computations. Finally, the case of attractive continuous curved walls is detailed, which represents a large variety of real systems (e.g. micro and mesoporous silica, zeolites, carbonaceous nanoporous materials, etc.). With the new way of computation proposed, a general solution is presented, valid for any shape of continuous pore surface, by considering mathematical properties of discrete geometry due to the discretisation of the computational space with FFT computations.     

(KN3)n(n=1~5)团簇结构与性质的密度泛函理论研究

利用密度泛函理论B3LYP方法, 在6-311G*基组水平上对(KN3)n(n=1~5)团簇各种可能的结构进行了几何结构优化, 预测了各团簇的最稳定结构. 并对最稳定结构的振动特性、成键特性、电荷分布和稳定性性质进行了分析研究. 结果表明, 叠氮化合物中叠氮基以直线型存在, KN3团簇最稳定结构为直线型, (KN3)n(n=2~3)团簇最稳定结构为环形结构, (KN3)n(n=4~5)团簇最稳定结构是由(KN3)2团簇最稳定结构形成的平面和空间结构. N-N 键键长在0.1156~0.1196 nm之间, N-K键键长在0.2357~0.2927 nm之间; 叠氮基中间的N原子显示正电性, 两端的N原子显示负电性, 且与K原子直接作用的N原子负电性更强, 金属K原子与N原子之间形成离子键. (KN3)n(n=1~5)团簇最稳定结构的IR光谱最强振动峰均位于2180~2230 cm-1, 振动模式为叠氮基中N-N键的反对称伸缩振动. 稳定性分析显示, (KN3)3团簇具有相对较高的动力学稳定性.     

(KN3)n(n=1~5)团簇结构与性质的密度泛函理论研究

利用密度泛函理论B3LYP方法, 在6-311G*基组水平上对(KN3)n(n=1~5)团簇各种可能的结构进行了几何结构优化, 预测了各团簇的最稳定结构. 并对最稳定结构的振动特性、成键特性、电荷分布和稳定性性质进行了分析研究. 结果表明, 叠氮化合物中叠氮基以直线型存在, KN3团簇最稳定结构为直线型, (KN3)n(n=2~3)团簇最稳定结构为环形结构, (KN3)n(n=4~5)团簇最稳定结构是由(KN3)2团簇最稳定结构形成的平面和空间结构. N-N 键键长在0.1156~0.1196 nm之间, N-K键键长在0.2357~0.2927 nm之间; 叠氮基中间的N原子显示正电性, 两端的N原子显示负电性, 且与K原子直接作用的N原子负电性更强, 金属K原子与N原子之间形成离子键. (KN3)n(n=1~5)团簇最稳定结构的IR光谱最强振动峰均位于2180~2230 cm-1, 振动模式为叠氮基中N-N键的反对称伸缩振动. 稳定性分析显示, (KN3)3团簇具有相对较高的动力学稳定性.     

Progress on tilted axis cranking covariant density functional theory for nuclear magnetic and antimagnetic rotation

Magnetic rotation and antimagnetic rotation are exotic rotational phenomena observed in weakly deformed or near-spherical nuclei, which are respectively interpreted in terms of the shears mechanism and two shearslike mechanism. Since their observations, magnetic rotation and antimagnetic rotation phenomena have been mainly investigated in the framework of tilted axis cranking based on the pairing plus quadrupole model. For the last decades, the covariant density functional theory and its extension have been proved to be successful in describing series of nuclear ground-states and excited states properties, including the binding energies, radii, single-particle spectra, resonance states, halo phenomena, magnetic moments, magnetic rotation, low-lying excitations, shape phase transitions, collective rotation and vibrations, etc. This review will mainly focus on the tilted axis cranking covariant density functional theory and its application for the magnetic rotation and antimagnetic rotation phenomena.     

Exact treatment of pairing correlations in Yb isotopes with covariant density functional theory

The effects of pairing correlation in Yb isotopes are investigated by covariant density functional theory with pairing correlations and blocking effects treated exactly by a shell model like approach(SLAP). Experimental one- and two-neutron separation energies are reproduced quite well. The traditional BCS calculations always give larger pairing energies than those given by SLAP calculations, particularly for the nuclei near the proton and neutron drip lines. This may be caused because many of the single particle orbits above the Fermi surface are involved in the BCS calculations, but many of them are excluded in the SLAP calculations.     

Deconfinement phase transition in a 3D nonlocal U(1) lattice gauge theory

We introduce a 3D compact U(1) lattice gauge theory having nonlocal interactions in the temporal direction, and study its phase structure. The model is relevant for the compact QED3 and strongly correlated electron systems like the t-J model of cuprates. For a power-law decaying long-range interaction, which simulates the effect of gapless matter fields, a second-order phase transition takes place separating the confinement and deconfinement phases. For an exponentially decaying interaction simulating matter fields with gaps, the system exhibits no signals of a second-order transition.     

Simulation of beam optics for ~(12)C+~(12)C scattering of RCNP by using Monte Carlo method

The Monte Carlo method is used to simulate the beam optics of the WS beam line of RCNP, Osaka University in order to know the effect of collimators on the beam line to control the beam spot. According to the simulation, we do not need to use the collimator to cut the beam and the beam angular resolution can be better than 0.05° in achromatic mode. In the present paper, the actual beam condition during the beam adjustment is listed. The accelerator can provide a 12 C beam in achromatic mode and the angular resolution σ=0.7775 mrad ±0.0030 mrad.     

密度泛函方法研究NiSin(n=1~13)团簇

基于第一性原理,利用密度泛函理论中的广义梯度近似(GGA)系统研究了NiSin(n=1～13)团簇,在充分考虑自旋多重度的基础上讨论了这些团簇的生长行为,电子性质及其磁性,结果表明:NiSin 1的基态结构是在NiSin的基态结构上带帽一个Si原子而得到;随着团簇尺寸的增大,Ni原子逐渐从吸附在sin团簇的表面位置移动到Sin团簇笼内;掺杂Ni原子提高了硅团簇的稳定性;NiSi10团簇的稳定性在所有团簇中是最高的;电子总是从si向Ni转移,Ni原子所带的电荷数不仅与Ni原子的配位数有关,还与Nisin团簇的基态结构密切相关;n=1～2时,团簇的自旋总磁矩为2 μB,当n≥3时,团簇的磁性消失,这可能与Ni原子内部较强的sp-d杂化以及si原子内部的s-p杂化有关.     

用密度泛函理论研究氨质子化团簇(NH_3)_nH~+(n=1～8)的结构

运用Gaussian 03W程序中的密度泛函B3LYP方法,在6-31 G(d)基组水平上对氨质子化团簇(NH3)nH (n=1～8)的可能的几何构型进行了结构优化,得到了该系列团簇的稳定结构及其对应的总能量.结果表明,氨质子化团簇的稳定结构是质子与一个氨分子结合形成一个NH 4离子核,其它氨分子通过氢键作用形成氨链后与该离子核的四个氢以氢键结合形成的,它们之间的结合力均为中强氢键.另外,我们还利用能量的二阶差分理论对团簇的稳定性进行了研究,并计算了团簇的平均束缚能,发现随着团簇尺寸的增大,团簇的平均束缚能逐渐减小.     

方阱链流体在固液界面分布的密度泛函理论研究

应用Yethiraj的加权密度近似泛函理论研究平板狭缝中方阱链流体的密度分布，系统的Helm holtz自由能泛函分为理想气体的贡献利剩余贡献两部分，其中剩余贡献部分分别采用刘洪 来等人建立的基于空穴相关函数的方阱链流体状态方程和Gil-Villegas等人提出的统计缔合 流体理论状态方程(SAFT-VR)结合简单加权密度近似计算.考察了不同链长、温度、系统密度 和壁面吸引强度下平板狭缝中方阱链流体的密度分布，并与Monte Carlo(MC)模拟结果进行 了比较.结果表明采用不同的状态方程对密度分布的计算有明显的影响，对于受限于硬壁狭 缝中的方阱链流体，温度和密度比较高时，两种状态方程计算的结果均与MC模拟符合得比较 好，在低温和低密度下效果变差，SAFT-VR方程的计算结果更接近于MC模拟结果.对于受限于 方阱壁狭缝中的方阱链流体，由于系统密度分布的非均匀性加强，采用两种状态方程计算的 结果均与MC模拟结果有一定偏差，寻找更合适的权重函数是进一步改进的关键. 关键词： 密度泛函理论 非均匀流体 密度分布 固液界面 方阱链     

Investigation the effect of lattice angle on the band structure in 3D phononic crystals with rhombohedral(II) lattice

In this paper, the propagation of acoustic waves in the phononic crystals (PC) of 3D with rhombohedral(II) lattice is studied theoretically. The PC are constituted of nickel spheres embedded in epoxy. The calculations of the band structure and density of states are performed with the plane wave expansion method in the irreducible part of the Brillouin zone (BZ). In this study, we analyze the dependence of the band structures inside (the complete band gap width) and outside the complete band gap (negative refraction of acoustic wave) on the lattice angle in the irreducible part of the first BZ. Also the effect of lattice angle has been analyzed on the band structure of the ( \( \bar{1}10 \) ) and (122) planes. Then, the equifrequency surface is calculated for the high symmetry point in the [111] and [100] directions. The results show that the maximum width of AEBG (0.022) in the irreducible part of the BZ of RHL2 is formed for (105^°) and no AEBG is found for γ > 150^°. Also, the maximum of the first and second AEBG width are 0.1076 and 0.0523 for γ = 133^° in the ( \( \bar{1}10 \) ) plane and the maximum of the first and second AEBG width are 0.1446 and 0.0998 for γ = 113^° in the (122) plane. In addition, we have found that frequencies in which negative refraction occurs is constant for all lattice angles.     

Recent development in SU(3) covariant baryon chiral perturbation theory

Baryon chiral perturbation theory (BChPT), as an effective field theory of low-energy quantum chromodynamics (QCD), has played and is still playing an important role in our understanding of non-perturbative strong-interaction phenomena. In the past two decades, inspired by the rapid progress in lattice QCD simulations and the new experimental campaign to study the strangeness sector of low-energy QCD, many efforts have been made to develop a fully covariant BChPT and to test its validity in all scenarios. These new endeavours have not only deepened our understanding of some long-standing problems, such as the power-counting-breaking problem and the convergence problem, but also resulted in theoretical tools that can be confidently applied to make robust predictions. Particularly, the manifestly covariant BChPT supplemented with the extended-on-mass-shell (EOMS) renormalization scheme has been shown to satisfy all analyticity and symmetry constraints and converge relatively faster compared to its non-relativistic and infrared counterparts. In this article, we provide a brief review of the fully covariant BChPT and its latest applications in the u, d, and s three-flavor sector.     

Study of ~3He inelastic scattering on ~(13)C and ~(14)C at 37.9 MeV

The differential cross sections of elastic and inelastic scattering of ³He ions on ¹³C and ¹⁴C have been studied at an energy of 37.9 MeV with a double folding model based on M3Y-Reid effective nucleon-nucleon interaction. The resulted parameters have been used for the standard Distorted Wave Born Approximation calculations of angular distributions corresponding to different excitations levels of ¹³C and ¹⁴C and deformation parameters have been deduced.