Effective period potential in a hybrid mesoscopic ring with Rashba spin–orbit interaction

We investigate theoretically the persistent charge current (PCC) and pure spin current (PSC) in a hybrid mesoscopic ring with Rashba spin–orbit interaction (RSOI). The PCC and PSC surviving in the ring would experience a periodic potential formed by the band offset of the constituent materials. Similarly, an effective tunnel barrier can be introduced by a region with different RSOI strength. This provides us a convenient way to manipulate the periodic potential by changing the RSOI strength through an electric field. With the increment of the RSOI strength, the PCC is suppressed, while the PSC presents an oscillatory pattern changing from negative to positive.     

托卡马克装置中高能离子的直接损失

通过严格求解导心坐标系下的哈密顿方程,提出了托卡马克装置中离子的真实轨道理论,并利用此理论对国际热核聚变实验堆(ITER)中α离子的真实轨道进行了数值模拟研究,获得了驻点轨道和近期理论预言的半俘获轨道.根据此真实轨道理论计算了ITER中α离子的直接损失率.结果发现,与所提出的真实轨道理论相比,以前的回旋平均理论大幅度低估了α离子的直接损失率,两种理论的损失率差值可达14%,对此差异进行了详细的分析并给出了物理上的解释.     

Ballistic spin-dependent transport of Rashba rings with multi-leads

Using the Landauer–Büttiker formula with the transfer matrix technique, we develop a formalism of the ballistic spin-dependent electron transport in the multi-lead Rashba rings. We give analytic formulas of the total conductance G_j, spin-σ conductance and spin polarization P_j of each outgoing lead j, and their resonant and antiresonant conditions. Analytic studying with numerical investigating Rashba rings with several symmetric and asymmetric leads, we find that G_j, and P_j oscillate with the incoming electron energy and the spin–orbit interaction (SOI) strength, and their antiresonances depend on the incoming electron energy, the SOI strength and the outgoing-lead angle with the incoming lead. For the symmetric-lead rings, G_j, and P_j have some symmetries, , and P_j = −P_N−j for symmetric leads, j and N − j, where the angles between the symmetric outgoing leads j and N − j and the incoming lead are γ_N−j = 2π − γ_j. The spin polarization of the outgoing lead with γ_j = π is exactly zero for even-N-symmetric-lead rings. These symmetries originate from the lead symmetry and time reversal invariance. For asymmetry-lead rings these symmetries vanish.     

Is the spin‐orbit coupling important in the prediction of the 51V hyperfine coupling constants of VIVO2+ species? ORCA versus Gaussian performance and biological applications

Density functional theory calculations of the (51)V hyperfine coupling (HFC) tensor A, have been completed for eighteen V(IV)O(2+) complexes with different donor set, electric charge and coordination geometry. A tensor was calculated with ORCA software with several functionals and basis sets taking into account the spin-orbit coupling contribution. The results were compared with those obtained with Gaussian 03 software using the half-and-half functional BHandHLYP and 6-311g(d,p) basis set. The order of accuracy of the functionals in the prediction of A(iso), A(z) and dipolar term A(z,anis) is BHandHLYP > PBE0 > B3PW > TPSSh > B3LYP > BP86 > VWN5 (for A(iso)), BHandHLYP > PBE0 > B3PW > TPSSh > B3LYP > BP86 > VWN5 (for A(z)), B3LYP > PBE0 ～ B3PW ～ BHandHLYP > TPSSh > BP86 ～ VWN5 (for A(z,anis)). The good agreement in the prediction of A(z) with BHandHLYP is due to a compensation between the overestimation of A(iso) and underestimation of A(z,anis) (A(z) = A(iso) + A(z,anis)), whereas among the hybrid functionals PBE0 performs better than the other ones. BHandHLYP functional and Gaussian software are recommended when the V(IV)O(2+) species contains only V-O and/or V-N bonds, whereas PBE0 functional and ORCA software for V(IV)O(2+) complexes with one or more V-S bonds. Finally, the application of these methods to the coordination environment of V(IV)O(2+) ion in V-proteins, like vanadyl-substituted insulin, carbonic anhydrase, collagen and S-adenosylmethionine synthetase, was discussed.     

Magnetic quantum oscillations in a monolayer graphene under a perpendicular magnetic field

The de Haas-van Alphen(dHvA) oscillations of electronic magnetization in a monolayer graphene with structureinduced spin-orbit interaction(SOI) are studied.The results show that the dHvA oscillating centre in this system deviates from the well known(zero) value in a conventional two-dimensional electron gas.The inclusion of SOI will change the well-defined sawtooth pattern of magnetic quantum oscillations and result in a beating pattern.In addition,the SOI effects on Hall conductance and magnetic susceptibility are also discussed.     

GEO and IGSO joint precise orbit determination

Experiments and analyses are carried out for GEO and joint GEO/IGSO precise orbit determination using data recorded by China's regional tracking network.Results show that joint GEO/IGSO orbit determination effectively solves the problem of poor observation geometry for GEO satellites.The laser radial evaluation thus confirms that precision is as good as less than 0.1 m.In the case of joint orbit determination,solving the empirical acceleration can reduce errors introduced by the imprecise solar radiation pr...     

低轨微小卫星及小碎片搜索/跟踪机动式大视场光电望远镜

有效反射面积小,运动速度快的空间低轨卫星和小碎片的日益增多对现有地基探测跟踪技术提出了挑战。本文分析了国外现有低轨小目标光电探测技术的发展现状,结合低轨小目标的探测需求,提出了一种用于低轨微小卫星及小碎片搜索/跟踪探测的机动式车载大视场光电望远镜设计方案。介绍了该望远镜的光学系统、跟踪架及载车,描述了它的工作模式和图像处理,讨论了系统的搜索和探测能力。结果表明,该望远镜对300 km轨道高度的目标搜索能力达到13.5星等（相当于直径5 cm目标）,可以满足搜索和跟踪低轨微小卫星及小碎片探测的实际需求。     

MnFe2O4晶体的基态能级和零场分裂参量

由不可约张量理论构成一个3d4/3d6离子三角(C3V)对称的晶体场和自旋-轨道相互作用哈密顿矩阵,由这个晶体场和自旋-轨道相互作用哈密顿矩阵被完全对角化后能够求出MnFe2O4晶体中的Fe2+离子的电子顺磁共振零场分裂参量D和F-a,计算了低自旋态(3L态)对电子顺磁共振零场分裂参量(D,F-a)的贡献.结果显示低自旋3L态对电子顺磁共振的零场分裂参量的贡献是较强的.理论计算的结果与实验值是相符的.     

Subharmonic and grazing bifurcations for a simple bilinear oscillator

In this paper, subharmonic and grazing bifurcations for a simple bilinear oscillator, namely the limit discontinuous case of the smooth and discontinuous (SD) oscillator are studied. This system is an important model that can be used to investigate the transition from smooth to discontinuous dynamics. A combination of analytical and numerical methods is used to investigate the existence, stability and bifurcations of symmetric and asymmetric subharmonic orbits. Grazing bifurcations for a particular periodic orbit are also discussed and numerical results suggest that the bifurcations are discontinuous. We show via concrete numerical experiments that the dynamics of the system for the case of large dissipation is quite different from that for the case of small dissipation.     

奇异伪辛群作用下子空间轨道的长度

设F_q是q个元素的有限域,q是2的幂,F_q~(2ν+δ+l)是F_q上2ν+δ+l维行向量空间,Ps_(2ν+δ+l,2ν+δ)(F_q)是F_q上级数为2ν+δ+l而秩为2ν+δ的伪辛群.F_q~(2ν+δ+l)在Ps_(2ν+δ+l,2ν+δ)(F_q)的作用下划分成一些子空间轨道Μ(m,2s+τ,s,∈,k;2ν+δ,2ν+δ).采用矩阵初等行变换的方法,给出轨道Μ(m,2s+τ,s,∈,k;2ν+δ,2ν+ε)的长度.