共查询到19条相似文献,搜索用时 46 毫秒
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置于均匀电场中的一簇球形颗粒,由于其内部的相互作用而耦合在一起.这致使簇的感应偶极矩与簇的几何结构,大小以及颗粒的介电常数等参量有关.试图通过已知的链的偶极矩确定任意大小长方结构的簇的偶极矩.假定颗粒链可以被具有同样偶极矩的一个等效介质球代替,并将具有空间结构的颗粒簇处理成面结构簇,再将面结构简化成一个颗粒链,从而确定簇的偶极矩.在这一过程中,通过不断增加等效球的尺寸,将颗粒间的相互作用包含在簇的偶极矩中.数值分析了立方结构簇的偶极矩,结果是可接受的.
关键词: 相似文献
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推广了一般导体和点电荷电像,用迭代电像法计算了两个导体球之间的作用力与电容,并做了推广以及精确性分析.进一步给出了多个导体球的一般计算方式.作为多导体球问题的例子给出了第三个无静电荷的导体球对两导体球体系的影响.给出了导体作用数值计箅的具体方式,并且为导体相互作用实质提供了清晰的物理图像. 相似文献
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用电像法将点电荷与中性导体球系统的电场化为一维点电荷分布系统的电场,导出电场线满足的方程,利用Mathematica软件画出了电场线簇图形,并对点电荷与接地导体球、点电荷与带电导体球两系统的电场线进行了描绘。 相似文献
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利用蒙特卡罗方法根据团簇-团簇凝聚(CCA)模型对由球形原始粒子凝聚而成的烟尘簇团粒子进行了模拟,用离散偶极子近似(DDA)方法对随机分布的烟尘簇团粒子的缪勒矩阵元素进行了数值计算,给出了不同入射波长情况下随机分布烟尘簇团粒子的缪勒矩阵元素与组成簇团粒子的基本粒子的粒径和数目的数值关系,为进一步研究随机分布簇团粒子的形成机理、形态特性、散射特性提供了一种理论方法.
关键词:
烟尘簇团粒子
缪勒矩阵
离散偶极子近似方法 相似文献
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带电细圆环与导体球壳系统的场分布 总被引:1,自引:0,他引:1
先依电象法,推导均匀带电圆环在金属导体球壳内的"象电荷";再在球坐标系下,根据电场强度的计算公式与Tay-lor展开式,计算出均匀带电细圆环在全空间的电场分布的级数形式解;进而结合唯一性定理和电场的叠加原理,获得带电细圆环与导体球壳系统的空间场分布. 相似文献
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过渡金属纳米结构表面吸附CO分子时会出现异常红外效应,这一现象可以用纳米结构表面吸附分子在外电场作用下产生局部凝聚从而相互作用能增加来解释.在前期研究的基础上,给出金属基底表面生长出的纳米颗粒为椭球状颗粒的理论计算结果.基于均匀外电场中金属纳米椭球颗粒按一定对称性排列的表面结构模型,用经典电磁学理论计算了纳米椭球颗粒表面附近的局域电场.在此基础上,将吸附的CO分子等效为偶极子,在考虑了偶极子与局域电场、偶极子之间以及偶极子与金属基底三种相互作用的情况下,用Monte-Carlo方法进行数值模拟,最后给出纳
关键词:
金属纳米结构表面
纳米椭球
吸附分子
局域电场 相似文献
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Sofia KantorovichRudolf Weeber Joan J. CerdàChristian Holm 《Journal of magnetism and magnetic materials》2011,323(10):1269-1272
We present simulations and analytical calculations for a system of magnetic nano-particles that possess a dipole moment that is shifted out of the center of mass, towards the surface, leading to a further asymmetry of the dipolar interaction. In our contribution, we discuss the peculiarities of ground state small clusters, both, with and without an external magnetic field. Small clusters help us to get an insight into the inter-particle interactions and form a building block for studies of larger systems. Without external magnetic field, the ground state structure changes from chains and rings with parallel alignment of moments, usually observed in dipolar particles (Prokopieva et al., 2009 [1]), to pairs and triangles with close to anti-parallel orientation of moments, when the shift of the dipole is increased. We also present magnetization properties of larger systems at finite temperature and observe the influence of the shift in particular on the initial slope of the magnetization curve, namely, the initial susceptibility. 相似文献
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Hajime Okamoto 《Optical Review》1995,2(6):407-412
This paper concerns the theoretical improvement of the discrete dipole approximation (DDA) to provide scattering properties of clusters of spherical monomers. The first scattering coefficient (al-term) in Mie theory is introduced to determine the dipole polarizability used in the DDA. In the al-term method, a spherical monomer in the cluster is replaced by a single dipole. The accuracy of this method is tested to calculate extinction and scattering cross sections by a single sphere, two-touching spheres and three collinear touching spheres. It is found that when each monomer is replaced by a dipole the al-term method is superior to the different types of DDA, e.g., the Lattice Dispersion Relation (LDR), at least for the target with the volume equivalent size parameter X, 0.2≦X≦2. This method also allows treatment of a relatively large sub-volume element which is replaced by a dipole, i.e. the size parameter of the monomer Xm∼1.5. Furthermore, a great reduction in memory requirement and computing time are achieved, e.g. for two touching spheres the al-term method requires only 6% of the total memory requirement and 0.008% of the total computing time for N=8448 with the LDR.Part of this work was done when the author was in the Institute of Physics, GKSS Research Center, Postfach 1160, D-21494 Geesthacht, Germany 相似文献
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We prove existence of a shape- and boundary-condition-independent thermodynamic limit for fluids and solids of identical particles with electric or magnetic dipole moments. Our result applies to fluids of hard-core particles, to dipolar soft spheres and Stockmayer fluids, to disordered solid composites, and to regular crystal lattices. In addition to their permanent dipole moments, particles may further polarize each other. Classical and quantum models are treated. Shape independence depends on the reduction in free energy accomplished by domain formation, so our proof applies only in the case of zero applied field. Existence of a thermodynamic limit implies texture formation in spontaneously magnetized liquids and disordered solids analogous to domain formation in crystalline solids. 相似文献
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研究了两个存在偶极相互作用的原子系统中的偶极平方压缩效应,讨论了原子偶极相互作用以及相位信息对压缩效应的影响,并进而探讨了原子偶极平方压缩与光场振幅平方压缩之间的关联. 相似文献
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为了研究扫描近场光学显微镜中探针和粗糙样品表面的耦合相互作用,提出了一种光耦合偶极子模型.在该模型中,探针和样品突起都由光极化偶极子表示,在准静态电磁场近似的情况下样品表面的诱导极化效应由影像偶极子表示,应用偶极子辐射理论可以得到系统的自洽场方程.此模型提供了一种直观分析扫描近场光学显微镜中探针和样品相互作用机理的方法.在此基础上,进一步讨论了金属样品的近场成像特点和其特有的局域光学共振现象.数值结果表明:不同于一般的介质样品,金属样品的近场图像与入射光频率直接相关,改变入射光的频率,获得的样品近场图像的形状和对比度都会发生变化.特别是当入射光频率处于样品极化共振范围内时,金属纳米粒子的极化率会出现光极化共振,这样就可以获得样品粒子的最大有效尺寸,为提高系统的分辨率提供了一条重要途径. 相似文献
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In this paper we overview our recent studies of anisotropic noble metal (e.g. gold and silver) nanoparticles, in which a combination of theory and experiment has been used to elucidate the extinction spectra of the particles, as well as information related to their surface enhanced Raman spectroscopy. We used wet-chemical methods to generate several structurally well-defined nanostructures other than solid spheres, including silver nanodisks and triangular nanoprisms, and gold nanoshells and multipods. When solid spheres are transformed into one of these shapes, the surface plasmon resonances in these particles are strongly affected, typically red-shifting and even splitting into distinctive dipole and quadrupole plasmon modes. In parallel, we have developed computational electrodynamics methods based on the discrete dipole approximation (DDA) method to determine the origins of these intriguing optical features. This has resulted in considerable insight concerning the variation of plasmon wavelength with nanoparticle size, shape and dielectric environment, as well as the use of these particles for optical sensing applications. 相似文献
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The quantum corrections to the thermodynamic properties of polar hard sphere fluids and fluid mixtures are estimated taking
into account the influence of dipole and quadrupole moments. Expressions are given for the second virial coefficient, free
energy and pressure and results are given for different values ofμ* andϑ*. The first order quantum correction arises due to the translational contribution only. The quantum effect increases with
density,μ* andϑ*. Numerical results are also estimated for binary mixtures of (i) hard spheres and dipole hard spheres and (ii) hard spheres
and quadrupole hard spheres. The ‘excess’ free energy for dipole hard sphere binary mixture is also reported. It is found
that the ‘excess’ quantum effect depends on the concentration and the particle diameter ratio and increases with increase
ofμ* andϑ*. 相似文献
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I. E. Mazets 《Technical Physics》2000,45(10):1238-1240
The dipole moment of each of two uncharged conducting spheres with radius R in an external electric field was calculated. The distance between the centers of the spheres is 2l. It was shown that, if R/l≲0.8, the influence of higher multipole moments is negligible. 相似文献