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2.
The electronic structure and magnetism of SmCo7-xZrx alloy are investigated using the spin-polarized MS-X. method. The results show that a few of electrons are transferred to the Sm(5d0) orbital due to orbital hybridization between Sm and Co atoms. The exchange interactions between 3d and 5d electrons are more important than the polarization effects of the conductive electrons, thus it is the main reason resulting in the long-range ferromagnetic order in SmCo7-xZrx. The Curie temperature of SmCo7-xZrx is generally lower than that of corresponding pure Co, which may be explained by the weaker average coupling strength between Co lattices due to some negative couplings mainly occurring of 2e site. The calculated results for the Sm5Co32Zr2 cluster may lead to a better understanding of why SmCo7-xZrx is stable phase. Since the spin-up DOS peak of d electrons at EF arises and the bonding of electrons at EF strengthens with increasing Zr concentration, which results in the internal energy of the system decrease, the stable ferromagnetic order forms in SmCo7-xZrx. 相似文献
3.
We investigate classical electronic collisions with a He(+) ion. Scattering functions, such as the scattering angle, collisional time, or energy of the outgoing electron, all exhibit an interesting hierarchial self-similar structure, which can be interpreted in terms of the indefinite number of electronic returns to the vicinity of the nucleus, encounters between electrons, and Keplerian excursions of electrons during the collisional processes. Based on this mechanism a binary coding is introduced to organize the dynamics of this three-body system and to provide an understanding of the self-similarity among generations of scale magnification, which yields escape rates that vary with the sectional cut into the parameter space. The self-similarity displayed within a single generation, on the other hand, can be simply tied to the periods of the two independent electronic excursions. The physical interpretation and the symbolic dynamics introduced here are generally useful for three-body collisional systems, including atomic, molecular, or stellar collisions. 相似文献
4.
Kai-Shue Lam I. Harold Zimmerman Jian-Min Yuan John R. Laing Thomas F. George 《Chemical physics》1977,26(3):455-486
Collion-induced emission in molecular systems in an intense laser field is studied using the semiclassical approach, with a view towards cooperative chemical and optical pumping in laser production. The formalism is developed with the electronic-field representation, which treats collision and radiative interaction on the same footing. Electronic-field surfaces can be regarded as forming spectra for spontaneous emission; and particular emission events can be accounted for by propagating classical trajectories on emission electronic-field surfaces. Pre-emission loss from the excited state is dealt with by propagating classical trajectories on a loss surface along a complex contour of emission branch points. This loss surface is derived on the basis of localized radiative couplings between electronic-field states and provides a framework to treat the general problem of discrete state-continuum interactions. The formalism is applied to a two-state, collinear exponential model to compute S-matrix elements and transition probabilities between asymptotic states. 相似文献
5.
通过水热方法,采用H3CAM(H3CAM=4-hydroxy-pyridine-2,6-dicarboxylic acid)与Cd(NO3)2.4H2O反应,合成了1个镉配位聚合物[Cd4(HCAM)4(H2O)8]n(1),并对其结构和荧光性质进行了研究。结构分析结果表明该配合物属于单斜晶系,C2/c空间群。四个HCAM2-配体桥联4个镉离子形成了1个四核镉单元。这些孤立的单元通过氢键作用形成了1个三维配位框架。研究表明,该配合物在室温下能发出兰色荧光。 相似文献
6.
在考虑了泵浦损耗及激光损耗的情况下,解析求解了阈值泵浦下的三能级光纤激光器速率方程组,获得了泵浦功率阈值的显函数解析表达式,泵浦功率沿光纤变化的隐函数表达式,以及用功率变化表示的各个能级的粒子数密度随位置变化的显函数表达式。并利用这些表达式对光纤激光器的阈值特性进行了研究,研究表明:泵浦功率阈值随泵浦损耗系数增大而增大;激光上能级粒子数密度随归一化位置呈下降趋势,而下能级粒子数密度的变化与此相反;泵浦功率阈值越大(光纤长度越长),净增益系数随归一位置下降就越快。所获得的结果适用于单包层和双包层光纤激光器。 相似文献
7.
The all-electron full potential augmented plane-wave plus local orbital (APW_Io) method with the local-density approximation (LDA) is used to calculate the static equation of state (EOS) and elastic constants of crystalline GaSe. After the full relaxation of atomic positions, the calculated band structure at ambient pressure is consistent with the experimental data to the extent expected to give the known limits of LDA one-electron energies. The equilibrium lattice parameters found here exhibit the usual LDA-induced contraction. However, constrained with the experimental cell volume, the interlayer separation exhibits an expansion due to the LDA underestimate of the weak interlayer bonding. The calculated values of elastic constants are in good agreement with acoustic measurements. The pressure derivatives of the lattice constants derived from the theoretical elastic constants are in very good agreement with x-ray spectra measurements. Two analytical EOSs have been determined at pressures up to 4.5 GPa. The pressure evolution of the structure indicates that the layer thickness decreases slightly under pressure. 相似文献
8.
介绍了一种基于反冲质子法和磁分析技术的氘氚聚变诊断方法, 适用于稳态及脉冲条件下的等离子体温度、燃料密度和中子产额的精确诊断. 设计了小型的原理性装置, 磁分析器使用高性能钕铁硼二极永磁铁, 焦平面上使用CR-39固体径迹探测器或PIN探测器测量质子位置分布. 使用239Pu α 源对磁分析器进行了实验标定, 建立了配套的模拟程序. 利用蒙特卡罗方法模拟分析了装置整体性能, 并在K-400加速器上进行了中子实验研究. 相似文献
9.
10.
Most thin films have different thermal expansion coefficients from their substrates, thus thermal stresses will be introduced into the films when the temperature is changed during annealing and service. Calculations of these stresses for grains in various crystallographic orientations have been made for seven BCC transition metals Cr, Fe, Mo, Nb, Ta, V and W. Neglecting W, which is isotropic and the stresses are equiaxial and without grain orientation (hkl) dependence, the BCC metals may be grouped into two classes. In the first class (Cr, Mo, Nb and V), the (100)-oriented grains have the largest stresses, while the stresses σ1 and σ2 in other (hkl)-oriented grains decrease linearly with the increase of the angle between (hkl) and (100), and with σ1 〈 σ2 except in (100)- and (lll)-oriented grains. In the second class (Fe and Ta), on the contrary, the (100)-oriented grains have the lowest stresses, and the stresses σ1 and σ2 in other (hkl)-oriented grains increase linearly with the increase of the angle between (hkl) and (100), and with σ1 〉 σ2 except in (100)- and (111)-oriented grains. 相似文献