Progress in organic spintronics

Recent progress in organic spintronics is given an informative overview, covering spin injection, detection, and trans-port in organic spin valve devices, and the magnetic field effect in organic semiconductors （OSCs）. In particular, we focus on our own recent work in spin injection and the organic magnetic field effect （OMFE）.     

1,1-二氨基-2,2-二硝基乙烯晶体热膨胀各向异性的模拟研究

对新型钝感高能炸药组分1,1-二氨基-2,2-二硝基乙烯（FOX-7）,考察并选择了适用的分子力场和超晶胞初始构型,通过303K-378K温度范围在NPT系综下的分子动力学模拟（MD）,得到常压下各温度的FOX-7晶体平衡构型,发现随温度升高晶体内分子的取向和堆积方式不变;通过线性拟合求算出线膨胀系数,发现αb明显较大而αc与αa接近但不相等;接着采用密度泛函理论(DFT)方法随各向棱长膨胀的能量变化进行了模拟计算,发现得到的能量变化成各向异性并与各向热膨胀系数相关,从而建立FOX-7晶体特定分子堆积模式与热膨胀各向异性的关联。     

MgnLa(n=2-6)掺杂团簇的密度泛函研究

采用密度泛函(DFT)中的B3LYP方法,选择CEP-31g基组,优化并得到了MgnLa(n=2- 6)小团簇的基态平衡结构,计算出了掺杂团簇的基态结构的平均键长、对称性、费米能级、能级间隙、束缚能、总能的二阶差分．结果表明,随着团簇原子数的增加,La原子更容易趋于团簇表面位置. 与未掺杂Mg团簇相比,La原子多采用取代其稳定基态结构的一个Mg原子形成掺杂团簇的稳定结构. 从有限的结果看,其中 Mg3La和 Mg6La的结构更为稳定．     

Automated derivation of optimal regulators for nonlinear systems by symbolic manipulation of Poisson series

Concepts of programmability and compact programmability are defined relative to a class of modified Poisson series. Lie-series-based canonical perturbation methods from astrodynamics are applied to the Hamiltonian system boundary-value problem, and more usual methods are applied to the perturbed Hamilton-Jacobi-Bellman partial differential equation, in order to obtain a complete set of equations for the perturbed optimal feedback control law for both infinite-time and finite-time regulator problems. The relative advantages of each approach are evaluated. A major aim of the paper is to determine the largest class of perturbations, within the set of Poisson series, for which the equations can be derived on a computer by symbolic manipulation. The more general the class, the more accurate the perturbation solution can be, for a given order. The solutions developed are complete; all that remains is to program them in order to have computerized derivations of the optimal nonlinear feedback control laws.This research was supported by NSF Grant No. ENG-78-10232. This paper was presented at the 1982 Conference on Information Sciences and Systems, Princeton, New Jersey, and appears in the Proceedings.     

Collective atomic spin squeezing and control

Using a quantum theory for an ensemble of two- or three-level atoms driven by electromagnetic fields in an optical cavity, we show that the various spins associated with the atomic ensemble can be squeezed. Two kinds of squeezing are obtained: on the one hand self-spin squeezing when the input fields are coherent ones and the atomic ensemble exhibits a large non-linearity; on the other hand squeezing transfer when one of the incoming fields is squeezed. Received 14 August 2001 and Received in final form 7 November 2001     

5D Dirac Equation in Induced-Matter Theory

According to an induced-matter approach, Liu and Wesson obtained the rest mass of a typical particle from the reduction of a 5D Klein–Gordon equation to a 4D one. Introducing an extra-dimension momentum operator identified with the rest mass eigenvalue operator, we consider a way to generalize the 4D Dirac equation to 5D. An analogous normal Dirac equation is gained when the generalization reduces to 4D. We find the rest mass of a particle in curved space varies with spacetime coordinates and check this for the case of exact solitonic and cosmological solution of the 5D vacuum gravitational field equations.     

Note: An Unusual Route to General Relativity Equation in Presence of Dust in Irrotational Motion

We show that the general relativity theory equation, in presence of pressureless matter (dust) in irrotational motion, can be recovered from a scalar-tensor like variational approach. In this approach, the kinetic energy, , of a dynamical scalar field , couples directly to gravity. The lagrangian, exempt of explicit matter term, is varied in the framework of the first order formalism, and a conformal transformation, restoring riemannian geometry, is made. In this approach, it turns out that a non-empty spacetime is necessarily four-dimensional.     

场源基本微元的对称性与场的性质

直接由标量基本微元（点源）和矢量基本微元（电流元等）的对称性和两个基本假设讨论基本微元产生的场矢量的性质。     

用半波带法讨论单缝夫琅和费衍射的课件演示与制作

根据半波带法的思路，介绍了利用计算机课件演示对单缝夫琅和费衍射的条纹光强与衍射角之间的关系，以便有效地化解教学难点，帮助学生对该知识点形成清晰的认识和深化理解，同时对课件制作要点作了简要说明。     

Universality principle and the development of classical density functional theory

The universality principle of the free energy density functional and the ‘test particle' trick by Percus are combined to construct the approximate free energy density functional or its functional derivative. Information about the bulk fluid radial distribution function is integrated into the density functional approximation directly for the first time in the present methodology. The physical foundation of the present methodology also applies to the quantum density functional theory.