几种元素在高温高密度下离子电离度的类氢平均原子模型计算

根据类氢平均原子模型对Ｆｅ，Ｔｉ，Ｓｉ和Ｍｇ的平均电离度进行了数值计算，结果表明，类氢平均原子模型计算与Ｓａｈａ方程方法以及Ｔｈｏｍａｓ－Ｆｅｒｍｉ模型方法的结果相差不大，利用类氢平均原子模型可对由高压引起的原子轨道畸变进行适当的修正，对修正方法进行了讨论并给出了算例。     

几种元素在高温高密度下离子电高度的类氢平均原子模型计算

根据类氢平均原子模型对Ｆｅ、Ｔｉ、Ｓｉ和Ｍｇ的平均电离度进行了数值计算，结果表明，类氢平均原子模型计算与Ｓａｈａ方程方法以及Ｔｈｏｍａｓ—Ｆｅｒｍｉ模型方法的结果相差不大，利用类氢平均原子模型可对由高压引起的原子轨道畸变进行适当的修正，对修正方法进行了讨论并给出了算例。     

氢及类氢离子光谱精细结构理论计算的改进

原子光谱数据是研究原子结构的重要参数,氢及类氢离子是原子物理和量子力学研究的理想体系.通过对氢及类氢离子光谱精细结构数据的研究发现,需要对Dirac提出的有关理论公式进行改进.本文在考虑了电子的自旋角动量与轨道角动量的耦合作用后,通过对Bohr理论中的电子运动角动量的修改,推导出单电子体系的电子速度公式,结合对Schr dinger的原子轨道能级表达式相对论效应修正,从而得出本文的氢及类氢离子光谱精细结构值的理论计算公式,应用此改进公式,所得的计算值与实验观测值符合得很好,计算结果也反映了氢及类氢离子光谱精细结构数据变化的规律性.     

氩离子原子过程参数的系统计算与评估：I 电子碰撞激发

 利用准相对论扭曲波玻恩近似加交换方法，在组态平均近似下，系统地计算了类氢、类氦、类锂氩离子n≤6的各组态之间的碰撞激发过程截面，并和已有的理论结果进行了详细的对比分析。计算结果和相对论扭曲波近似的计算结果符合得很好，相对偏差一般都小于10%。由于没有考虑共振效应，计算的结果与强耦合方法的计算结果在入射电子能量较低的情况下有较大偏差，其他情况则符合较好，相对偏差一般在15%以内。该方法可以方便地计算大量应用所需的原子过程参数。     

氩离子原子过程参数的系统计算与评估：Ⅰ电子碰撞激发

利用准相对论扭曲波玻恩近似加交换方法，在组态平均近似下，系统地计算了类氢、类氦、类锂氩离子n≤6的各组态之间的碰撞激发过程截面。并和已有的理论结果进行了详细的对比分析。计算结果和相对论扭曲波近似的计算结果符合得很好，相对偏差一般都小于10％。由于没有考虑共振效应。计算的结果与强耦合方法的计算结果在入射电子能量较低的情况下有较大偏差，其他情况则符合较好，相对偏差一般在15％以内。该方法可以方便地计算大量应用所需的原子过程参数。     

类镉离子5s^2 ^1S0→5s5p^1,3P1跃迁振子强度的计算

应用屏蔽氢模型计算类Ｃｄ离子５ｓ２１Ｓ０→５ｓ５ｐ１Ｐ１共振跃迁振子强度，引入ｊ－耦合中校正系数Ｋ和混合角θ导出５ｓ２１Ｓ０→５ｓ５ｐ３Ｐ１跃迁振子强度表达式。计算结果和其他作者进行了比较，并给出某些讨论。     

电子碰撞类锂钙离子共振电离截面和速率系数

在库仑－坡恩交换近似及被我们改进了屏蔽常数定义和算法的Ｚ－标度类氢模型下，计算了类锂钙离子被电子碰撞的共振电离截面积速率系数。     

一种能量守恒的双向耦合简正波水声传播模型

针对非水平边界条件近似处理所引起的双向声场能量不守恒问题,提出了一种满足能量守恒的双向耦合简正波模型。在模型的建立中,严格考虑了非水平界面的边界条件,并依据介质运动方程和连续性方程推导了便于数值计算的耦合微分方程。同时,结合能量守恒方程和不同海底参数下的数值计算,对模型的准确性进行了研究。由理论分析和仿真结果可以看出,边界条件的严格考虑将导致边界修正项的产生,而边界修正项的引入确保了耦合系数满足对称性和模型所计算的声场满足能量守恒,使得本模型可充分考虑边界水平变化对声场的影响,实现非水平分层波导中双向场的准确计算。      

高剥离氩离子电子碰撞电离参数评估

基于可以得到的理论和实验数据，对利用准相对论组态平均近似系列程序包计算的类氢、类氯、类锂氩离子的碰撞电离原子参数进行了评估，发现对基态类氢、类氯和类锂氩离子的碰撞电离，在不考虑共振过程的情况下，我们的加交换的准相对论扭曲波方法的计算结果是可靠的，但对于激发态的碰撞电离过程。还有待于可靠的数据比较，此外对不同离化度的离子有很好的类氢近似标度规律。     

类Ne—Ti离子能级及振子强度的理论计算（相对论多组态HF模型）

本文通过对多组态Ｄｉｒａｃ－Ｆｏｃｋ型自洽场基础上的ＧＲＡＳＰ程序进行扩充和改造，采用平均能级模型对类氖钛离子１５个组态共８９个能级一次性自洽地进行计算，计算中采用了双参量Ｆｅｒｍｉ分布有限核模型，考虑了Ｂｒｅｉｔ修正、真空极化和自能效应对能级的修正。ＬＳ与ｊｊ耦合标号分别由最大混合系数来标定，并与其它标号系统进行了比较。计算了８９个能级之间所有可能的电偶极、电四极和磁偶极的谱线跃迁概率和振子强度     

Slater绝缘体的磁性和能带计算研究

Slater相变是一种由于反铁磁序形成而导致的金属—绝缘体相变.本文采用第一性原理密度泛函计算方法研究了两种Slater绝缘体材料NaOsO_3和Cd_2Os_2O_7的电子结构,进而研究了反铁磁序排列、自旋轨道耦合和电子关联对其电子结构以及相变性质的影响.研究结果表明,非磁相的NaOsO_3具有金属性;而G型线性反铁磁结构是驱动NaOsO_3发生Slater相变的磁基态.此外,研究结果表明,非磁相的焦绿石Cd_2Os_2O_7的能带结构在费米能级处是连续的,表现为金属性;并且带有磁阻挫的Cd_2Os_2O_7发生Slater相变的条件十分苛刻,只有在自旋轨道耦合和1.8 eV电子关联的共同作用下一种全进—全出非线性反铁磁结构才能使其发生Slater相变.说明全进—全出非线性反铁磁结构是使Cd_2Os_2O_7发生Slater相变的磁基态,而自旋轨道耦合和1.8 eV的电子关联在消除磁阻挫上起到了关键作用.     

Ab initio calculation of spin-orbit coupling constants for gaussian lobe and gaussian-type wave functions

The spin-orbit coupling constants of a series of diatomic compounds containing first row atoms have been calculated using ab initio molecular wave functions with gaussian lobe and gaussian-type basis sets. In most cases, fair agreement with the experimental values has been achieved. It is pointed out that multicentre terms have almost no effect on the spin-orbit coupling constant. Furthermore, suggestions for a one-electron approximation using effective nuclear charges are presented.     

Conductance oscillations of a spin-orbit stripe with polarized contacts

We investigate the linear conductance of a stripe of spin-orbit interaction in a 2D electron gas; that is, a 2D region of length l\ell along the transport direction and infinite in the transverse one in which a spin-orbit interaction of Rashba type is present. Polarization in the contacts is described by means of Zeeman fields. Our model predicts two types of conductance oscillations: Ramsauer oscillations in the minority spin transmission, when both spins can propagate, and Fano oscillations when only one spin propagates. The latter are due to the spin-orbit coupling with quasibound states of the non propagating spin. In the case of polarized contacts in antiparallel configuration Fano-like oscillations of the conductance are still made possible by the spin orbit coupling, even though no spin component is bound by the contacts. To describe these behaviors we propose a simplified model based on an ansatz wave function. In general, we find that the contribution for vanishing transverse momentum dominates and defines the conductance oscillations. Regarding the oscillations with Rashba coupling intensity, our model confirms the spin transistor behavior, but only for high degrees of polarization. Including a position dependent effective mass yields additional oscillations due to the mass jumps at the interfaces.     

自旋—轨道耦合下冷原子的双反射

随着中性冷原子气体的人造自旋-轨道耦合的实验实现,近年来人们开始关注与之相关的可能应用,其中包括自旋-轨道耦合下原子反射镜的研究.本文在前人研究的基础上,考虑一束自旋-轨道耦合的冷原子气体入射到有限高势垒的情形,通过将部分反射和全反射情况进行对比,发现了与之前研究不同的性质.我们发现,在全反射条件下,反射原子的极化率随入射角变化较大,而随自旋-轨道耦合强度和原子入射能量的变化较小.但在发生部分反射的情况下,反射原子的极化率不仅随入射角变化较大,随自旋-轨道耦合强度和原子的入射能量变化也十分明显.我们仔细研究了自旋-轨道耦合原子气体的反射性质并讨论了其可能的应用.     

Evaluation of molecular spin-orbit integrals by a gaussian expansion method

A method is presented for the evaluation of molecular multi-centre spin-orbit integrals of Coulomb, hybrid and exchange types using cartesian gaussian functions. It is shown that if gaussian bases are employed the spin-same-orbit integrals reduce to one-electron field integrals and the spin-other-orbit integrals to two-electron field integrals. The final formulae for these integrals are found to be convenient for computer programming. Some relationships among the nuclear attraction, the field and the field-gradient integrals as well as among the electronic repulsion, the two-electron field, and the zero-field splitting integrals are discussed in connection with the spin-orbit integrals. Some calculations are carried out for the radicals CH₂ and NH.     

On the sound field of a shallow spherical shell in an infinite baffle

A method is presented for calculating the far field sound radiation from a shallow spherical shell in an acoustic medium. The shell has a concentrated ring mass boundary condition at its perimeter representing a loudspeaker voice coil and is excited by a concentrated ring force exerted by the end of the voice coil. A Green's function is developed for a shallow spherical shell, which is based upon Reissner's solution to the shell wave equation [Q. Appl. Math. 13, 279-290 (1955)]. The shell is then coupled to the surrounding acoustic medium using an eigenfunction expansion, with unknown coefficients, for its deflection. The resulting surface pressure distribution is solved using the King integral together with the free space Green's function in cylindrical coordinates. In order to eliminate the need for numerical integration, the radiation (coupling) integrals are solved analytically to yield fast converging expansions. Hence, a set of simultaneous equations is obtained which is solved for the coefficients of the eigenfunction expansion. These coefficients are finally used in formulas for the far field sound radiation.     

Spin-orbit coupled spinor Bose-Einstein condensates

An effective spin-orbit coupling can be generated in a cold atom system by engineering atom-light interactions. In this Letter we study spin-1/2 and spin-1 Bose-Einstein condensates with Rashba spin-orbit coupling, and find that the condensate wave function will develop nontrivial structures. From numerical simulation we have identified two different phases. In one phase the ground state is a single plane wave, and often we find the system splits into domains and an array of vortices plays the role of a domain wall. In this phase, time-reversal symmetry is broken. In the other phase the condensate wave function is a standing wave, and it forms a spin stripe. The transition between them is driven by interactions between bosons. We also provide an analytical understanding of these results and determine the transition point between the two phases.     

Cusped gaussian wave function. I

The present paper describes the first part of an investigation into the possibility of finding a set of simple functions for the construction of molecular wave functions which satisfies two essential requirements: that the number of basis functions required to produce a given accuracy be comparable to the number of Slater functions required to give the same accuracy, and that the molecular multicentre integrals should be considerably easier to evaluate than those over Slater functions. It is shown that a basis made up of 1s gaussians supplemented by a single ‘cusp function’ of the form

may be expected to satisfy the requirements for the s-orbitals in atoms other than hydrogen. Calculations of the ground-state orbital approximations of the helium and beryllium atoms show that an inner-shell 1s orbital can be satisfactorily described by the cusp function and two gaussians, whilst subsequent s-orbitals should require not more than two or three gaussians per orbital to produce better than ‘double-zeta’ accuracy.     

Effect of Anisotropic Spin-Orbit Coupling on the Ground State of Bose-Einstein Condensate in an External Potential

Spin-orbit coupled Bosonic atoms confined in external potentials open up new avenues for quantumstate manipulation and will contribute to the design and exploration of novel quantum devices.Here we consider a quasi-two-dimensional spin-orbit coupled Bose-Einstein condensate confined in an external harmonic potential,with emphasis on the effects of anisotropic spin-orbit coupling on the equilibrium ground-state structure of such a system.For the cases with spin-orbit coupling solely in x- or y-axis direction,the ground-state structure can develop to the well-known standing wave phase,in which the two components always form an alternative density arrangement.For a two-dimensional anisotropic spin-orbit coupling,the separated lumps first become bend,then form two rows of stripe structure along y direction with further increasing the strength of spin-orbit coupling in x-direction.Furthermore,the distance between these two rows of stripe structure is also investigated in detail.