He-Na2体系低温下的冷碰撞研究

在已经拟合好的He-Na₂体系势能面上,根据原子-双原子分子的非反应性碰撞动力学的相关基本理论,在空间固定坐标系下,采用严格的密耦方法求解了He原子和Na₂分子的转动非弹性碰撞动力学方程.并对He-Na₂体系的微分散射截面、积分截面作了详细的分析,结果与实验符合得比较好.结果表明：（1）弹性散射（Δj=0）截面远大于非弹性截面;（2）较小Δj的跃迁主要产生前向散射,随着Δj的增加,后向散射的几率增加 关键词： 2体系')" href="#">He-Na₂体系 密耦方法 微分散射截面 积分截面     

Novel modification of anhydrous transition metal oxalates from powder diffraction

The known metal–C₂O₄ structures may be divided into two modifications, α and β. The α‐modification has an order–disorder struxture, revealing one‐dimensional disordering of the metal–oxalate chains, and the β‐modification is ordered. The crystal structures of orthorhombic γ‐MnC₂O₄ {poly[μ‐oxalato‐manganese(II)]; space group Pmna , a = 7.1333 (1), b = 5.8787 (1), c = 9.0186 (2) Å, V = 378.19 (1) ų, Z = 4 and D_x = 2.511 Mg m⁻³} and γ‐CdC₂O₄ {poly[μ‐oxalato‐cadmium(II)]; space group Pmna , a = 7.3218 (1), b = 6.0231 (1), c = 9.2546 (2) Å, V = 408.13 (1) ų, Z = 4 and D_x = 3.262 Mg m⁻³} have been obtained from powder diffraction patterns. The structures are isostructural. Each metal atom in each structure is coordinated by seven O atoms which belong to five oxalate ions. The crystal packing, which contains noticeable cavities in the [101] and [001] directions, is not close packed and essentially differs from the known disordered α‐ and ordered β‐modifications of transition metal oxalates. This modification seems to be metastable. It was found that a spontaneous γ→β phase transition takes place for γ‐CdC₂O₄.     

直流清洗电场对储存环聚焦参数修正作用的研究

研究了直流清洗电场对储存环聚焦参数的修正作用.认为该清洗电场形成的横向振荡数移位,与储存束流闭轨实时位置有关.指出电极沿环不对称分布的此类清洗电场,会破坏储存环聚焦结构的对称性,降低储存环的接受度,在一定条件下,对注入积累束流过程有负作用.     

AuTa14S2 — Zentrierte (Au,Ta)13-Ikosaeder organisiert nach dem Motiv einer kubisch dichten Packung

AuTa₁₄S₂ – Centred (Au,Ta)₁₃ Icosahedra Organized According to the Motif of a Cubic Close Packing The tantalum-rich phases of composition Au_xTa_15?xS₂ (0.4 < x < 1.1) were prepared by arc-melting of appropriate compressed mixtures (Au, Ta, Ta_1.35S₂) and subsequent annealing of the samples in sealed molydenum crucibles. Brittle crystals with silver lustre were grown in tantalum ampoules at 1 700 K within two days using iodine as a chemical transport agent. In contrast to Vegard's rule the lattice parameters of the rhombohedral phases which are isostructural with Pd₁₅P₂, shrink with increasing gold content. The structures were determined from Rietveld fits of powder X-ray diffraction spectra and confirmed by a crystal structure analysis of a merohedral twinned crystal of Au_0.7Ta_14.3S₂: a = 747.7(2) pm, α = 59.84(2)°, R3 , Z = 1, 760 reflections (F² > 2σ(F²)), 30 variables, R(F) = 0.048. The parts of the volumina of the domains with distinct orientations are 0.346(4) and 0.654. Topologically the structure corresponds to a cubic close packed arrangement of Ta₁₂-icosahedra with all non-tetrahedral interstices being filled. Gold accumulates preferentially in the centres of the icosahedra. The remaining metal atoms – two per formula and site – populate the ?octahedral sites”? which are encased in stretched polyhedra limited by 32 triangulated faces. The ?tetrahedral sites”? are occupied by the sulfur atoms which themselves have a ninefold, triangulated tetrakaidecahedral coordination. The complete occupation of interstices together with the specific orientation of the gold stabilized icosahedral (Au,Ta)₁₃-clusters ensure a tetrahedral close packing of all atoms. The distortions of the packing are quantitatively analysed in terms of dihedral angles and deviations of the tetrahedral edge lengths from the mean and are compared with those of other tcp structures.     

Charge exchange in C6+ + H (1s) collisions at low energies

The low‐energy single electron capture cross‐sections by C⁶⁺ from H atoms have been evaluated employing the semiclassical, impact parameter, close‐coupling method based on a molecular expansion augmented with the plane‐wave translation factor. Using the method of Bates and Carson, the exact Born–Oppenheimer eigenfunctions and eigenvalues are calculated. Eight‐state coupled equations are solved to obtain transition probabilities and thereby evaluate capture cross‐sections. Our calculated capture cross‐sections agree well with other theoretical and experimental results. At these energies it is found that the capture into the n = 4 manifold of the C⁵⁺ remains the main contributor to the charge exchange process. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003     

A mixed problem for the Laplace operator in a domain with moderately close holes

We investigate the behavior of the solution of a mixed problem in a domain with two moderately close holes. We introduce a positive parameter ε and we define a perforated domain Ω_ε obtained by making two small perforations in an open set. Both the size and the distance of the cavities tend to 0 as ε → 0. For ε small, we denote by u_ε the solution of a mixed problem for the Laplace equation in Ω_ε. We describe what happens to u_ε as ε → 0 in terms of real analytic maps and we compute an asymptotic expansion.     

Close‐to‐convexity of normalized Dini functions

In this paper necessary and sufficient conditions are deduced for the close‐to‐convexity of some special combinations of Bessel functions of the first kind and their derivatives by using a result of Shah and Trimble about transcendental entire functions with univalent derivatives and some newly discovered Mittag–Leffler expansions for Bessel functions of the first kind.     

Complexity in close binary evolution

The complex nature of close binary evolution is briefly reviewed. Population synthesis calculations of zero‐age cataclysmic variable stars (ZACVs) are presented using a common envelope (CE) efficiency parameter, α_CE, that is a function of the core mass of the primary. Specifically, we investigate the possibility that α_CE is different for CE evolution involving red giant branch (RGB) primaries than for asymptotic giant branch (AGB) primaries. We calculate a sequence of model orbital period distributions in present‐day ZACVs for 11 different combinations of efficiency parameters (α_RGB, α_AGB). We find that if CE evolution is much less efficient for RGB primaries than for AGB primaries (α_RGB ～ 0.1 or less), the number of CVs that form below 2 h is significantly decreased compared with standard constant α_CE models. © 2008 Wiley Periodicals, Inc. Complexity, 2008.     

关于m-HPK(n1,n2,n3,n4)-残差图

本文研究了3-维超平面完备残差图以及m 重3-维超平面完备残差图. 利用容斥原理以及集合的运算性质等方法, 分别获得了3-维超平面完备残差图和m 重3-维超平面完备残差图的最下阶以及二者的唯一极图, 将文献[1] 中定义的残差图从平面推广到超平面上.     

关于相关系间的同构映射

建立了相关系间的同构映射,给出了相关系间同构映射的一些等价条件,并通过具体的同构映射揭示出相关系的一些内在本质.