从流密度的Fourier分量出发导出多极矩表达式

从运动电荷产生的流密度入手,通过Fourier变换引入各级多极矩的表达式.     

变形核的电荷密度分布

本文应用原子核的宏观模型提出了一种比较简单的计算变形核电荷密度的方法.具体计算了¹⁹²Os、¹⁵⁴Gd、¹⁵²Sm、¹⁷⁴Yb、及^{144,148,150,152}Sm等原子核的电荷密度分布.结果表明,宏观模型计算的结果能较好地与实验测量结果相符合.因此,只要根据变形核基态到各转动态跃迁几率或电多极矩的实验值,则可按本文方法,从理论上预言变形核的电荷密度分布.     

从流密度的Fourier分量出发民出多极矩表达式

从运动电荷产生的流密度入手，通过Ｆｏｕｒｉｅｒ变换引入各级多极矩的表达式。     

固氩高压物态方程和弹性性质的密度泛函理论计算

 用平面波赝势方法结合局域密度近似密度泛函理论（DFT-LDA）计算了零温下固态氩晶体在压力0~82 GPa的p-V关系和弹性性质,计算结果与静高压实验数据符合较好,计算结果表明局域密度近似方法能较好地描述固氩晶体高压下的性质,采取合理的方法和计算参数,惰性气体固态晶体高压下的力学性质可以比较准确地计算出来,这可为一些还不能通过实验进行研究的物态分析提供借鉴。     

染料敏化太阳能电池光敏剂卟啉儿茶酚的密度泛函和含时密度泛函研究

用密度泛函理论的杂化密度泛函B3LYP方法研究了太阳能电池光敏荆5,10,15.三苯基-20-(3,4-二羟基苯)卟啉(卟啉儿荼酚,TPP-cat)的几何结构、电子结构、IR和Raman特性.用自然键轨道方法分析了电荷布居和成键性质.计算结果表明,最强的IR吸收峰位于1175.81 cm-1处,最强的Raman活性位于1587.18 cm-1处.采用含时密度泛函计算了TPP-cat在水溶液中的电子吸收谱,其Soret带和Q带均指认为π→π*跃迁,在大约354 cm-1处的跃迁与一个光诱导分子内电荷转移过程有关.     

薄栅氧化层中陷阱电荷密度的测量方法

提出了一种测量陷阱电荷密度的实验方法,该方法根据电荷陷落的动态平衡方程,利用恒流应力前后MOS电容高频CV曲线结合恒流应力下栅电压的变化曲线求解陷阱电荷密度及位置等物理量.给出了陷阱电荷密度的解析表达式和相关参数的提取方法和结果.实验表明这种方法方便而且具有较高的精度 关键词： 薄栅氧化膜 经时击穿 恒流应力 陷阱电荷密度     

等效的DBHF方法研究有限核性质

利用等效的Dirac Brueckner Hartree-Fock(DBHF)方法,即用密度相关的核子–介子耦合常数在相对论平均场近似下,考虑了重排列项,研究了有限核的性质.介子–核子耦合常数的密度相关性是由考虑了核子短程关联的DBHF方法来确定的,要求在每个密度下用相对论平均场方法得到的核子自能与用DBHF得到的自能一致.计算了核物质性质及有限核基态性质,并着重讨论了重排列项对Ca及Pb同位素链结果的影响.考虑重排列项作用后使计算的核电荷均方根半径增大,更好地符合实验值.     

静电雾化过程中雾滴空间电荷密度的实验测试

采用金属网笼法对静电雾化中雾滴群的空间电荷密度进行了实验测试，结果表明该方法可以大致了解雾化空间中雾滴群的局部带电情况。实验数据进一步表明，荷电雾滴的带电特性在不同空间位置处有极大的差异性，雾化轴心处的雾滴电荷密度最高，雾滴电荷密度沿径向方向逐渐减小。当施加电压增大时，不同空间位置处的雾滴电荷密度均有所提高，但电荷密度...     

离子推力器推力密度特性

离子推力器推力密度分布对航天器轨道维持和修正具有重要影响.采用粒子模拟-蒙特卡罗碰撞方法模拟束流等离子体输运过程,分析束流多组分粒子喷出数量和速度等微观参数,并计算得到单孔束流推力,结合放电室出口等离子体密度分布,进一步对推力密度分布特性分析,最后开展实验验证.研究结果显示:束流中单价离子、双荷离子以及交换电荷离子的推力贡献比分别为84.63%,15.35%和1.82%,可见推力主要来源于束流中的单价离子和双荷离子,交换电荷离子对推力贡献很小;推力密度分布具有较好的中心轴对称性,从推力器中心沿着径向先快速下降后趋于缓慢;与实验结果对比,经验模型相对误差约为4.1%,数值模型相对误差约为2.8%,相比经验模型,数值模型具有更好的准确性.研究结果可为离子推力器推力密度分布均匀性等优化提供参考.     

内掺氮富勒烯N_2@C_(60)的几何结构和电子性质的密度泛函计算研究

采用密度泛函理论中的广义梯度近似对内掺氮富勒烯N2@C60的几何结构和电子性质进行计算研究.发现在N2@C60中,氮倾向以分子形式存在于C60中心处.键长分析、能级图、态密度图和电荷分析表明内掺氮分子对C60几何结构和电子结构带来的影响甚微.     

Analysis on experimental valence charge density in germanium at RT and 200 K

The electronic structure and hence the valence charge distribution of germanium at 296 and 200 K has been elucidated from structure factors measured by X-ray diffraction experiment using maximum entropy method (MEM) and multipole model. The methods adopted here are used to extract the fine details of the charge density distribution in the valence region. The charge density evaluated using both the models along the bond path and at the mid bond positions are compared and found to confirm the covalent bond existing in the solid. Topology of the charge density in the crystal is analysed and the critical points determined reveal unique spatial arrangement of valence charge in the direction normal to the bonding direction. The Laplacian of the charge density is also analysed for the understanding of the spatial distribution and the partitioning of the valence charge. The local charge concentration and the mapping of the electron pairs of the Lewis and valence shell electron pair repulsion (VSEPR) models have been done using electron localization function (ELF) and localized orbital locator (LOL).     

Free energy of a spin glass

We give the theory of a model spin glass of the Sherrington-Kirkpatrick type. Determining that the free energy is given by the potential function of a two-dimensional electrostatic medium, we find exact expressions for this quantity in terms of a multipole expansion of the charge distribution. We also obtain the internal energy, entropy, and specific heat in the form of explicit integrals over the multipole distributions. Pending the outcome of a quantitative investigation into the structure of these functions, here we discuss their properties in a qualitative way.     

Elastic charge density representation of the interaction via the nematic director field

The interaction between particle-like sources of the nematic director distortions (e.g., colloids, point defects, macromolecules in nematic emulsions) allows for a useful analogy with the electrostatic multipole interaction between charged bodies. In this paper we develop this analogy to the level corresponding to the charge density and consider the general status of the pairwise approach to the nematic emulsions with finite-size colloids. It is shown that the elastic analog of the surface electric charge density is represented by the two transverse director components on the surface imposing the director distortions. The elastic multipoles of a particle are expressed as integrals over the charge density distribution on this surface. Because of the difference between the scalar electrostatics and vector nematostatics, the number of elastic multipoles of each order is doubled compared to that in the electrostatics: there are two elastic charges, two vectors of dipole moments, two quadrupolar tensors, and so on. The two-component elastic charge is expressed via the vector of external mechanical torque applied on the particle. As a result, the elastic Coulomb-like coupling between two particles is found to be proportional to the scalar product of the two external torques and does not directly depend on the particles' form and anchoring. The real-space Green function method is used to develop the pairwise approach to nematic emulsions and determine its form and restrictions. The pairwise potentials are obtained in the familiar form, but, in contrast to the electrostatics, they describe the interaction between pairs (dyads) of the elastic multipole moments. The multipole moments are shown to be uniquely determined by the single-particle director field, unperturbed by other particles. The pairwise approximation is applicable only in the leading order in the small ratio particle size-to-interparticle distance as the next order contains irreducible three-body terms.     

Magnetic multipole moments

Literature definitions of magnetic multipole moment operators are shown to be at variance, and new definitions are formulated which are consistent with a general multipole interaction hamiltonian and with the radiation field of a dynamic charge distribution. The applicability of traceless multipole moments is examined.

The multipole hamiltonian is used to derive expressions for some magnetic quadrupole distortion tensors. For those describing the quadrupole moment induced by a magnetic field and by a field gradient the number of independent components for various molecular symmetries is evaluated.     

Topological analysis of charge density in heptasulfur imide (S7NH) from isolated molecule to solid

Intra and intermolecular interactions of heptasulfur imide (S₇NH) are investigated in terms of topological properties analyses, such analyses are applied to both experimental (multipole model) and theoretically calculated (DFT and PDFT calculations) charge densities of the isolated molecule and of the crystal. The same analyses are also applied to a multipole model density obtained from theoretically (PDFT) derived structural amplitudes. The covalent bond character of S-N, N-H and S-S bonds are well described in terms of density, ρ_b, and total energy density, H_b, at the bond critical point r_c, though it is clear that the S-S bonds are weaker shared interactions than those of N-H and S-N bonds. Lone pair electron regions of sulfur and nitrogen atoms are revealed as the local charge concentration site from the Laplacian of charge density. The even weaker intermolecular interactions are well characterized; these include the N-H?S hydrogen bonding, N?S binding interactions and S?S binding interactions. All these intermolecular binding interactions are closed-shell interactions. The Laplacian of charge density demonstrates a directional intermolecular binding interaction. The corresponding intermolecular binding energies are derived by MP2/6-311+G(d,p) calculations. Atomic graph of each atom of the molecule is described in detail by the vertices, edges and faces of the polyhedron around the nucleus to illustrate such directional interactions.     

Current conservation and electric multipoles

New forms of the electric multipole operators are derived. We have uniquely and optimally isolated those components of the nuclear current density which are constrained by current conservation, and replaced them by multipole fields based on the charge density. This generalization of the work of Siegert is shown by means of a sum rule to have a very different structure from conventional forms which were designed to be effective in the long wavelength limit. The new form puts the electric and magnetic multipoles on the same footing: The current ebters only as the magnetization density, $\text{μ}\text{(x) =}\text{x × J(x)}\text{2}$.     

CHARGE DENSITY DISTRIBUTIONS OF DEFORMED NUCLEI

A simple calculation method for charge for charge density distributions of deformed nuclei by using macroscopic model has been proposed.The calculations of charge density distributions for ¹⁹²Os,¹⁵⁴Gd,¹⁵²Sm,¹⁷⁴Yb, and ^{144,148,150,152}Sm nuclei have been performed.The results show that the calculated charge densities are in good agreement with experiments.Consequently,on the base of experimental data of the transition probabilities for ground state to 2⁺,4⁺,6⁺ rotational states or its electric multipole moments,The charge density distributions of deformed nuclei can be predicted theoretically by this method.     

Density functional theory for reactions of astrophysical interest

For astrophysical processes nuclear reactions close to the particle emission threshold are of particular importance. As representative examples we investigate pairing resonances and new low-energy multipole modes in light and heavy exotic nuclei with a large charge asymmetry. As a common theoretical background, density functional theory and Fermi Liquid Theory are used. In particular, we consider the spectroscopy particle unstable systems, carrying the properties of open quantum systems. Results for the continuum spectroscopy of ¹⁰Li, the neutron-rich carbon isotopes, and the electromagnetic response of Sn-isotopes ¹³⁸Ba are presented.