共查询到20条相似文献,搜索用时 109 毫秒
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改进了文献中报导的Boltzmann基本方程。与Boltzmann基本方程相比,改进后的Boltzmann方程更全面地描述了电子与基态氩原子碰撞的物理过程,并能计算出整个能量区间的电子分布。利用Boltzmann基本方程和改进的Boltzmann方程,对电子束泵浦氩中能量大于氩原子第一激发态能量(11.56eV)的高能电子分布函数进行了理论计算。计算中,选取了电子碰撞氩的微分电离截面和激发截面的解析表达式。对计算所得的稳态电子分布函数以及达到稳态分布所需的特征时间进行了分析和讨论。 相似文献
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本文研究了关於电子激发原子核的理论。对当原子核由於各多极核矩和电子的电磁相互作用而引起的激发截面进行了一些估计,并且导出表示电子和X射线对原子核激发现象相互关系的公式。这公式仅是原子核能级跃迁中的能量、角动量、和宇称的函数,而不因其他原子核性质而变。把理论的结果和激发In115的试验测量作了一些比较。不过因为缺乏充分的实验测量数据,没能从这比较上得到肯定的结论。於是建议了一些可能进行的研究原子核能级的试验方法。 相似文献
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研究了超短超强激光脉冲与薄膜靶相互作用中产生的电子热发射.当超短激光脉冲与薄膜靶相互作用时,首先入射超短脉冲激光对吸收深度内的自由电子进行热激发,接下来热激发电子将能量传递到附近的晶格,再通过电子和晶格二体系的热传导,以及电子晶格间的热耦合,将能量传递到材料的内部.因此,电子在皮秒级甚至更短的时间内不能与晶格进行能量耦合,使电子温度超出晶格温度很多,电子热发射就变得非常明显了.用双温方程联合Richardson-Dushman方程的方法对飞秒脉冲激光照射金属靶的电子热发射进行了研究,结果发现电子热发射对飞 相似文献
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A. A. Klyukanov A. V. Catanoi 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,49(3):275-281
Microscopic many-body theory for electronic properties
of solid states is developed with an emphasis on the role of correlation
memory effects. Heisenberg equation of motion, fluctuation-dissipation
theorem and operators of commutation have been used to calculate
multiplasmon transmission electron energy loss spectra. Multiquantum
integral kinetic equation for the longitudinal complex dielectric function
is derived. Strong interaction between high-energy probe beam electrons penetrating the
solid state and plasma of valence electrons is taken into account. It is
shown that average number of high-frequency plasmons generated in every
collision process is more than one for typical values of metal parameters.
It is obtained that excitation of a good few plasmons is simultaneous event.
Calculated multiplasmon structure of electron energy loss spectra coincides
with experimental. 相似文献
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Yu-Liang Liu 《Physics letters. A》2019,383(12):1336-1340
By introducing the phase transformation of electron operators, we map the equation of motion of an one-particle Green's function into that of a non-interacting one-particle Green's function where the electrons are moving in a time-depending scalar potential and pure gauge fields for a D-dimensional electron gas, and we demonstrate that the electronic correlation strength strongly depends upon the excitation energy spectrum and collective excitation modes of electrons. It naturally explains that the electronic correlation strength is strong in the one dimension, while it is weak in the three dimensions. 相似文献
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激发态过程的多体理论方法 总被引:2,自引:0,他引:2
描述多电子体系的绝大部分参量可实验测量,如吸收光谱、发光光谱和激子效应等,都涉及电子激发态的正确描述。密度泛函理论(DFT)框架内的局域密度近似(LDA)作为第一性原理基态理论,即基于Kohn-Sham方程的解,是研究多粒子体系基态性质非常有力的工具。然而,体系激发态的第一性原理理论及其计算要比基态的理论计算复杂得多。关键问题在于描写基态和激发态时,粒子间的交换关联相互作用并不相同,而对于非均匀相互作用多粒子体系的交换关联能至今仍不清楚。不过,近年来关于激发态问题的研究,先后发展了许多描述电子激发态的理论,最重要的是基于准粒子概念和Green函数方程的多体微扰理论和含时间密度泛函理论(TDDFT)以及与此相关的描述电子-空穴相互作用的Bethe-Salpeter方程在凝聚态物理问题中的应用。其中最关键的物理量是粒子的自能算符Σ,它描述Hartree近似之外的交换和关联效应。虽然这些理论不可避免地也要引入某些近似,如对于Σ的一个好的近似就是Hedin的GW近似方法。对许多实际凝聚态体系的计算机模拟结果表明,GW近似是描述激发态问题相当成功的理论方法。将Hartree-Fock(HF)理论与LDA相结合,但采用非局域屏蔽交换代替HF方法中的局域非屏蔽交换相互作用,建立广义的KS方程(GKS),得到所谓屏蔽交换局域密度近似(sX-LDA)方法。我们在平面波自洽场方法PWscf程序包的基础上,发展了PW scf-sX-LDA方法,也是处理激发态问题及材料设计的有效方法。将评述激发态过程多体理论各种方法的发展和意义,讨论这些多体理论方法之间的联系和差异,并在此基础上介绍它们在解决半导体带带跃迁(或带隙偏小问题)、半导体及其微结构中的激子效应等重要领域的应用和成果。 相似文献
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Gerhard Hanisch 《Zeitschrift für Physik B Condensed Matter》1965,4(4):297-326
Following the many-body treatment of exciton byHaken andSchottky we represent the electronic polarization of the lattice induced by the excess electron and the hole in the Hamiltonian as well as in the wave function by introducing localized pair states and their coupling with the exciton particles. By application of a unitary transformation the pair states may be eliminated and one obtains the effective Schrödinger equation of an exciton consisting of particles dressed with polarization clouds. The coupling coefficients are determined by a minimum condition for the polarization energy. The effective interaction law between electron and hole and their effective masses are investigated explicitly. By transformation of the Schrödinger equation into a system of difference equations and solution of the corresponding secular equation one obtains an expression for the binding energy of the lowest exciton state in the alkali halides, which represents a connection of the “excitation” and “transfer” models. For the iodides of Na, K and Rb the binding energies were calculated using an approximative estimate for the various matrix elements involved. They are in good agreement with the experimentally observed energy differences between the first absorption peak and the small shoulder which indicates the position of the band edge. 相似文献
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R. Asgari 《Solid State Communications》2007,141(10):563-568
We present a theory of the pair distribution function g(z) and many-body effective electron-electron interaction for the one dimensional (1D) electron liquid. Our approach involves the solution of a zero-energy scattering Schrödinger equation for where we implemented the Fermi hypernetted-chain approximation including the elementary diagram corrections. We present numerical results for g(z) and the static structure factor S(k) and obtain good agreement with data from diffusion Monte Carlo studies of the 1D system. We calculate the correlation energy and charge excitation spectrum over an extensive range of electron density. Furthermore, we obtain the static correlations in good qualitative agreement with those calculated for the Luttinger liquid model with long-range interactions. 相似文献
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Within the scope of many-body Green functions we derive a formally exact expression for the (d,p)-stripping amplitude, which resembles the DWBA for this reaction. However, the distorted wavefunctions in the entrance and exit channel are defined with respect to the most general expressions for the optical potentials, as they are given by the mass operators of corresponding Dyson equations for correlation functions. In the same way the transition operator is a complicated many-body quantity which explicitly depends on the deuteron energy and contains for example contributions coming from the core excitations of the target nucleus. In this paper we are mainly interested in the latter effect and a numerical estimation of a crude model for the many-body effects of the transition operator reveals no pronounced (sharply resonant) energy dependence. The essential difference of our paper to other publications on the same subject is that we are dealing with the “Dyson equation” approach developed recently for higher Green functions. 相似文献