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Basis functions of a new type—specifically, exponential-trigonometric functions depending on all six interparticle distances—have been proposed for the Coulomb four-body problem. A method has been developed for computing nine-dimensional integrals determining the matrix elements of the Hamiltonian for a four-body system and featuring these functions. The efficiency of the approach that relies on the proposed basis functions has been tested by calculating the e + e ? e + e ?, p +μ? p +μ?, μ+ e ?μ+ e ?, and p + e ? p + e ? molecules.  相似文献   

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The method of correlated basis functions is applied to the electron system in a metal. To overcome the twofold difficulty of large particle number and long-range Coulomb interaction in metals, a new optimal cluster decomposition for arbitrary correlated wave functions is derived. With this method, not only ground-state properties, but also thermal averages and response functions can be calculated from a given set of correlated basis functions. The appropriate synthesis of correlated wave functions including physically expected properties of subsystems as for instance partially filled inner shells in transition metals is discussed in detail.  相似文献   

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高斯光束下的圆屏衍射   总被引:5,自引:2,他引:5  
王忠纯 《大学物理》2003,22(6):21-23,34
计算分析了用高斯光束作光源时,圆屏衍射轴线上的光强分布规律,并与球面波入射的情况进行了对比.  相似文献   

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A simple method for determination of effective dielectric constants is proposed that allows a close-spaced two-dimensionally periodic dielectric layer with rectangular elements to be replaced by a homogeneous and anisotropic layer of the same thickness. The method makes it unnecessary to solve the complicated problem of determination of the fields within the elements for calculation of the plane-wave reflection and transmission coefficients in a long-wave approximation, which considerably simplifies the calculations. Comparison with known solutions obtained by rigorous methods for one-dimensionally periodic gratings shows exact agreement of the results. The method is easily extended to magnetodielectric media as well as to multicomponent media, including those whose dielectric constants are functions of the coordinate perpendicular to the layer.Academician A. L. Mints Radio-Engineering Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 36, No. 3-4, pp. 286–294, March–April, 1993.  相似文献   

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Recently, Agrawal and Thamer suggested a new sequence of summation-integral type operators using the Baskakov basis function. We find a generating function of the q-Baskakov basis function and suggest a q-analog of the operators. We estimate moments, give a recurrence formula, and obtain some direct results. We also mention the possibility of improving the q-operators and, finally, suggest a Bézier-type variant of the operators discussed here.  相似文献   

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Application of net-point methods to the solution of the layer-to-layer transition problem leads to the necessity to restrict the domain and formulate artificial boundary conditions. In the present work the introduction of an artificial coaxial for reducing the original problem to a waveguide diffraction problem is applied. The test results of the finite-element program that we developed, which demonstrate the high accuracy of the method, are considered. The investigated dependence of the solution on the artificial boundary location shows the rapid convergence of the method.  相似文献   

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Using the discrete source method, we develop an algorithm for solving the three-dimensional problem of wave scattering by a plane grating consisting of acoustically soft or acoustically stiff bodies. An efficient algorithm is proposed for determining the periodic Green’s function of the grating. Numerical results are obtained for different geometries of the grating elements. The fulfillment of the energy conservation law is verified along with the fulfillment of the boundary condition at the surface of the central grating element.  相似文献   

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We propose a new method for solving the two-dimensional problem of diffraction by a cylindrical body in a layered medium. Unlike the traditional methods, the boundary-value problem is reduced to solving the integral equation for the scattering pattern of the body. As an illustration of this method, we consider the problem of scattering by a round cylinder located in a dielectric layer between two homogeneous half-spaces. Technical University of Communication and Information Science, Moscow, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 7, pp. 874–888, July, 1998.  相似文献   

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Raj Kumar 《Optik》2011,122(2):105-109
Schlieren is among the oldest and widely used optical techniques for detection of change in refractive index in transparent media. Present work demonstrates the effect of the position of schlieren element in the Airy pattern on the schlieren interferogram. It has been shown that the amplitude of the diffracted wave, starting from schlieren element and serving as an inbuilt reference beam for the schlieren diffraction interferometer, becomes maximum when schlieren element diffracts light from the Airy disk. Effect of F-number of the optical system on schlieren pattern is also demonstrated via observations on the amplitude of diffracted light.  相似文献   

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根据博里叶光学传输表达式,利用数值计算方法,首次给出了小于衍用极限的小孔处于夫朗和菲区时,理想光束和像差光束经过它之后的波面相位变化.  相似文献   

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标量衍射理论是最早用于分析光盘读出光场的理论,它用标量函数描述光场,计算和理解读出过程比较简单。在只读光盘(CD及其兼容类)发展的过程中,它一直扮演着基础理论的角色。综述和比较了1970年以来的一些标量衍射理论,重点讨论了光盘信息符的模型及标量衍射分析方法等。对各种方法的优缺点作了评述,对如何定量描述标量衍射理论在分析高密度光盘方面的局限性问题提出了建议。  相似文献   

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It is shown that, apart from the purely elastic scattering of X-rays, their inelastic coherent scattering by phonons can play, in some cases, a significant part in the formation of reflection curves for multiple X-ray diffraction. This process may affect the interference pattern for weak reflection, and it must be taken into account when extracting the triplet phase, as was demonstrated by an analysis of the experimental rocking curves obtained for the coplanar three-beam diffraction by a KDP crystal.  相似文献   

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