高离化态类镍离子电子碰撞激发过程的相对论扭曲波理论研究

利用相对论扭曲波方法和新发展的研究电子碰撞激发过程的计算程序REIE06,系统计算了电子碰撞激发高离化态类镍Gd³⁶⁺和Rn⁵⁸⁺—U⁶⁴⁺(Z=86—92)离子从基态到4l(l=s,p,d,f)次壳层精细结构能级的碰撞强度和截面.研究了随等电子系列变化时,从基态到与X射线激光有关的3d⁹4p和3d⁹4d激发态能级的电子碰撞激发截面随Z的变化,讨论了强的组态相互作用对高离化态类镍离子截面的影响.通过对Gd³⁶⁺离子涉及X射线激光跃迁的相关能级电子碰撞激发速率系数的计算,分析了等离子体中电子温度对碰撞过程的影响.同时,目前部分计算结果与以往的理论结果进行了比较,得到了很好的一致性. 关键词： 电子碰撞激发 相对论扭曲波方法 高离化态类镍离子     

类铍离子磁四极M2 2s2 1S0—2s2p3P2 (Z=10—103)禁戒跃迁

利用全相对论多组态Dirac-Fock方法系统地计算了高离化类铍离子的磁四极M2 2s²¹S₀—2s2p³P₂ (Z=10—103)自旋禁戒跃迁的能级间隔、跃迁概率和振子强度，计算中考虑了重要核的有限体积效应，Breit修正和QED修正，所得结果和最近的实验数据以及理论值进行了比较，结果表明：高原子序数的高电荷离子(Z≥70)磁四极M2自旋禁戒跃迁几乎可以和中性原子的光学允许跃迁相比拟，不仅在天体等离子体中，在ICF和MCF高温激光等离子体中，磁四极自旋禁戒跃迁和其他自旋禁戒跃迁（磁偶极、电四极）一样不容忽视，在双电子复合、不透明度、自由程等理论计算中应该考虑其影响. 关键词： 磁四极M2 能级间隔 跃迁概率 振子强度     

磁场退火对Co基熔体抽拉丝巨磁阻抗效应的影响

对Co基熔体抽拉非晶丝进行了普通炉内退火和不同磁场强度（500 Oe,1600 Oe,4000 Oe）下的横向和纵向磁场退火,利用HP4192阻抗分析仪和Lakeshore7407VSM分析了退火态样品的巨磁阻抗（GMI）效应和软磁性能.研究结果表明,纵向磁场降低了环向各向异性,纵向磁场退火样品GMI效应降低且GMI曲线为单峰,最大阻抗变化率ΔZ/Z为131%,磁场响应灵敏度为7%/Oe;而横向磁场提高了环向畴体积,增加了环向各向异性场,导致退火样品GMI曲线随频率升高由单峰转 关键词： 非晶丝 巨磁阻抗效应 退火     

高剥离态Au、U离子电离势的相对论计算

采用全相对论量子力学GRASP 2程序平均能级AL模型,考虑到核的有限体积效应、Breit和QED效应,系统地计算了金和铀的高剥离态的部分离子态的电离势,将所得的计算结果和文献报道的实验值进行比较.结果表明,考虑高剥离态原子的高阶修正后,高剥离态离子的电离势的计算值与实验数据之间的误差基本消除.     

等离子体屏蔽效应对类氢离子能级结构和辐射跃迁性质的影响

在Debye-Hückel屏蔽近似下,基于相对论Dirac-Fock方法,发展了包括等离子体屏蔽效应的自洽场计算程序.使用该程序研究了等离子体屏蔽效应对类氢离子能级结构和辐射跃迁性质的影响.结果表明,当原子处于等离子体环境中,所有束缚态能级向连续态移动, 移动量随着屏蔽长度的减小而增大.振子强度随屏蔽长度的变化也表现出了相同的规律.进一步分析了相对论效应和等离子体屏蔽效应的耦合,发现对于中Z元素,相对论效应和等离子体屏蔽效应存在较强的耦合.讨论了等离子体屏蔽效应对原子精细结构能级的影响.计算发现,由于等离子体屏蔽效应,原子的能级次序发生了变化,κ简并被消除. 关键词： 等离子体屏蔽 Debye-Hückel 模型 能级结构 跃迁概率     

一类q变形广义相干叠加态的量子统计性质

研究了一类q变形广义相干态叠加态|ψ>=a|β>+be^iφ|βe^iδ>的量子统计性质，结果表明此种叠加态普遍存在压缩效应和光子反群聚效应.相干态间的位相差，叠加系数的位相差和广义相干态之间内积的幅值和位相的变化对迭加态的压缩效应和反群聚效应起着重要的作用. 关键词： q变形')" href="#">q变形 广义相干态 压缩效应 反群聚效应     

描述高自旋弱耦合系统的广义积算符

本文提出了Z算符与角动量积算符相结合的广义积算符,用于描述高自旋弱耦合系统NMR实验谱。给出了高自旋系统在自旋耦合作用下的演变公式,Z算符在脉冲作用下的变化公式。以氘(D)为例,计算了重聚INEPT,DEPT和同核COSY实验谱,并对计算方法作了讨论。     

组态相互作用和相对论修正对类He离子双电子谱的影响

研究了组态相互作用和相对论修正对低Z(原子序数)及中等Z类He离子双电子谱的影响,使用准相对论及非相对论的Hartree-Fock自洽场方法计算了描写双电子伴线的原子参数。计算结果表明,(1)组态相互作用对类He离子双电子诺有显著影响;(2)对中等Z的类He离子,仅以能量微扰的形式计入相对论修正是不足够的,为了获得更加精确的计算结果,不仅要考虑相对论修正对单、双激发态能量的影响,而且要考虑该效应对径向波函数的影响。     

电子碰撞Ga,As, Pt,W和Au原子Lα X射线产生截面的理论计算

利用修改后的MBELL模型,研究了L壳层的相对论效应和离子效应对快电子碰撞电离Lα X射线产生截面的影响.通过在BELL模型中引入相对论效应和离子效应,基于相对论性的L壳层的电子碰撞电离截面的理论,计算了Ga,As,Pt,W和Au的L壳层电子碰撞电离截面,并将其转化成Lα X射线产生截面,计算结果表明考虑到相对论效应和离子效应后,修改后的MBELL的Lα X射线产生截面结果明显优于BELL的计算结果,并和最近的文献实验数值 关键词： 快电子 Lα射线')" href="#">Lα射线 电离截面 相对论效应     

电离度效应对重类氢离子跃迁概率的影响

在高电离态类氢离子的新势函数模型下, 电子近核区域运动的相对论效应、有限核效应、量子电动力学(QED)等效应已被电离度效应所取代. 利用包含电离度效应的类氢离子波函数, 系统研究了电离度效应对重类氢离子电偶极跃迁概率的影响. 发现电离度效应使类氢He+9至Pm+60离子的跃迁概率相对增加3.55 %-10.38 %. 这有利于实验研究者估价自己测量到的原子或离子状态的正确性.     

Natural J coupling (NJC) analysis of the electron lone pair effect on NMR couplings: 2. The anomeric effects on 1 J (C,H) couplings and its dependence on solvent

The electronic origin of the influence of the anomeric effect (negative hyperconjugative interaction, NHI) on the Fermi contact (FC) term of ¹ J(C, H) couplings has been studied from a theoretical point of view at the DFT-B3LYP level. The HN=CH₂, molecule was chosen as the primary model compound, in which both FC ¹ J(C, H) couplings were decomposed into bond contributions with the natural J coupling dissection approach (NJC). Differences between the ¹ J (C, H)^FC couplings for C——H bonds in synperiplanar and antiperiplanar orientations with respect to the nitrogen non-bonding electron pair closely follow the experimental trend. They are made up chiefly of three NJC contributions: ‘bond’, ‘direct lone pair’ and the ‘carbon-core orbitals’. The NHI influence on these terms was studied by applying the natural bond orbital (NBO) deletion procedure to the charge transfer interaction into the antiperiplanar (C——H) antibond (n(N)→(C——H)?) prior to the NJC dissection calculation. The dielectric solvation effect on both the total FC terms and the respective NJC contributions was estimated by carrying out the calculations using the polarization continuum model. Inhibition of the anomeric effect is evident when the solvent polarity is increased. NHI saturates rapidly with increasing solvent dielectric. Specific solute-solvent interaction effects on ¹ J(C, H) couplings were estimated by evaluating molecular complex models of the form CH₂=HN…S (S = H₂O and DMSO).     

Nuclear size correction to the hyperfine splitting in low- hydrogen-like atoms

The finite nuclear size effect on the hyperfine splitting of low-Z hydrogen-like atoms is studied in the external field approximation. A simple non-relativistic formula is proposed which expresses the nuclear size correction to the hyperfine splitting in terms of moments of the nuclear charge and magnetization distribution. The numerical results obtained via this formula are compared with corresponding results derived by means of the Zemach formula. A relativistic formula for the nuclear size correction to the hyperfine splitting is also derived. Received 18 March 2002 / Received in final form 14 November 2002 Published online 28 January 2003 RID="a" ID="a"e-mail: plunien@physik.tu-dresden.de     

传统中子幻数稳定性的研究

在考虑了BCS理论的相对论平均场模型框架内,通过系统研究N=8,20,28,50,82和126六条同中子素链中每个元素费米面附近的单粒子能级间隔、粒子数占有概率比以及原子核体系的粒子数偏离随质子数的变化规律,讨论了传统中子幻数的壳结构在从中子滴线区到质子滴线区整个核谱上的稳定性,预言只有在轻核的丰中子区域,传统的中子幻数效应才可能消失,并把计算结果和最近的文献报道作了比较. 关键词： 相对论平均场模型 能级间隔 占有概率 粒子数偏离     

Magnetar crust electron capture for $$^{}$$Co and $$^{56}$$56Ni

Based on the relativistic mean-field effective interaction principle and random phase approximation theory in superstrong magnetic fields (SMFs), we present an analysis of the influence of SMFs on the electron Fermi energy, nuclear blinding energy, single-particle level structure and electron capture for \(^{55}\)Co, and \(^{56}\)Ni by the shell-model Monte Carlo method in the magnetar’s crust. The electron capture rates increase by two orders of magnitude due to an increase in the electron Fermi energy and a change in single-particle level structure by SMFs. Then the rates decrease by more than two orders of magnitude due to an increase in the nuclear binding energy and a reduction in the electron Fermi energy by SMFs.     

Disturbance of the shell structure of neutron-rich nuclei in the oxygen-magnesium region

The effects related to nuclear deformation and their influence on the shell structure and nuclear properties have been investigated. Calculations were performed within the self-consistent theory of finite Fermi systems. The possibility of existence of strongly deformed nuclei at the neutron drip line and behind it, such as ²⁸O, ³⁹Na, and ^41–43Na, is discussed.     

Effect of size quantization on the effective mass in ultrathin films ofn-Cd3As2

An attempt is made to investigate the effects of size quantization on the effective mass in ultrathin films ofn-Cd₃As₂. It is found that the effective mass at the Fermi level depends on the size quantum number due to the effect of crystal-field splitting, resulting in different effective masses at the Fermi level corresponding to different electric subbands. It is also observed that the different effective masses closely approach each other, for a given film thickness, with increasing electron concentration and, for a given electron concentration, with increasing film thickness.     

Remnant Fermi surface in a pseudogap regime of the two-dimensional Hubbard model at finite temperature

A precursor effect on the Fermi surface in the two-dimensional Hubbard model at finite temperatures near the antiferromagnetic instability is studied using three different itinerant approaches: the second order perturbation theory, the paramagnon theory (PT), and the two-particle self-consistent (TPSC) approach. In general, at finite temperature, the Fermi surface of the interacting electron systems is not sharply defined due to the broadening effects of the self-energy. In order to take account of those effects we consider the single-particle spectral function A(, 0) at the Fermi level, to describe the counterpart of the Fermi surface at T = 0. We find that the Fermi surface is destroyed close to the pseudogap regime due to the spin-fluctuation effects in both PT and TPSC approaches. Moreover, the top of the effective valence band is located around = (π/2,π/2) in agreement with earlier investigations on the single-hole motion in the antiferromagnetic background. A crossover behavior from the Fermi-liquid regime to the pseudogap regime is observed in the electron concentration dependence of the spectral function and the self-energy. Received 8 September 2000 and Received in final form 20 December 2000     

Generalized Parton Distributions of the Pion on the Transverse Lattice

The quark-generalized parton distributions of the pion are calculated from light-cone wavefunctions in transverse lattice gauge theory at large N_c. The pion effective size is found to decrease with increasing momentum transfer. An analytic ansatz, consistent with finite bound-state light-cone energy conditions, is given for the light-cone momentum dependence of the wavefunctions. This leads to simple, universal predictions for the behaviour of the distributions near the endpoints, complementing numerical DLCQ data.     

Nuclear structure effects in the isotope shift with halo nuclei

Corrections to atomic energy levels due to nuclear structure effects are discussed. These are the finite nuclear size combined with relativistic and recoil corrections, and the nuclear polarizability. Good understanding of these effects is necessary for interpretation of high-precision measurements of the isotope shifts with neutron-rich nuclei ^6,8He, ¹¹Li and ¹¹Be. The summary of the results of the accurate atomic structure calculations is presented also.