共查询到20条相似文献,搜索用时 640 毫秒
1.
F. A. Buot 《Journal of statistical physics》1990,61(5-6):1223-1256
A formal derivation of a generalized equation of a Wigner distribution function including all many-body effects and all scattering mechanisms is given. The result is given in integral operator form suitable for application to the numerical modeling of quantum tunneling and quantum interference solid state devices. In the absence of scattering and many-body effects, the result reduces to the noninteracting-particle Wigner distribution function equation, often used to simulate resonant tunneling devices. The derivation uses a Weyl transform technique which can easily incorporate Bloch electrons. Weyl transforms of self-energies are derived. Various simplifications of a general quantum transport equation for semiconductor device analysis and self-consistent numerical simulation of a quantum distribution function in the phase-space/frequency-time domain are discussed. Recent attempts to include collisions in the Wigner distribution-function approach to the numerical simulation of tunneling devices are clearly shown to be non-self-consistent and inaccurate; more accurate numerical simulation is needed for a deeper understanding of the effects of collision and scattering. 相似文献
2.
A. Muriel 《Physics letters. A》2013,377(16-17):1161-1165
From a time evolution equation for the single particle distribution function derived from the N-particle distribution function (A. Muriel, M. Dresden, Physica D 101 (1997) 297), an exact solution for the 3D Navier–Stokes equation – an old problem – has been found (A. Muriel, Results Phys. 1 (2011) 2). In this Letter, a second exact conclusion from the above-mentioned work is presented. We analyze the time symmetry properties of a formal, exact solution for the single-particle distribution function contracted from the many-body Liouville equation. This analysis must be done because group theoretic results on time reversal symmetry of the full Liouville equation (E.C.G. Sudarshan, N. Mukunda, Classical Mechanics: A Modern Perspective, Wiley, 1974). no longer applies automatically to the single particle distribution function contracted from the formal solution of the N-body Liouville equation. We find the following result: if the initial momentum distribution is even in the momentum, the single particle distribution is reversible. If there is any asymmetry in the initial momentum distribution, no matter how small, the system is irreversible. 相似文献
3.
Assuming that field theoretic Green’s functions scale, expressions for correlation function, number density, pressure are
obtained for a relativistic statistical many-body system. The scaling parameter is related to anomalous dimension and is a
measure of interaction. The effect of this interaction on the critical mass of dwarf stars is studied and is not found to
be insignificant. A mass radius relation is deduced. The Chandrasekhar limit is reproduced in the limit of non-interaction. 相似文献
4.
Yu.N. Ovchinnikov V.Z. Kresin 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(3):297-302
The relaxation of an electron excited to the high energy region, is accompanied by the creation of various excitations (plasmons,
quasi-particles, phonons). The stages of this many-body, non-stationary phenomenon (cascade) are described microscopically.
The electron distribution function n(ɛ, t) and characteristic times for the whole energy range, are calculated.
Received 7 February 2003 Published online 11 April 2003 相似文献
5.
A. Isihara 《Annalen der Physik》1979,491(4):241-252
A statistical treatment of the electromagnetic fields of a fully ionized plasma shows that there are two types of radiation. One of the radiation fields is determined by the time change of the distribution function and is characteristic of such plasmas. When the time change is due to the many-body couplings of the charges in the plasma, the radiation can be related to the nonequilibrium stress tensor. In particular, for large distances the radiation is determined by the total internal pressure in a way similar to the classical Larmor formula for a point charge. 相似文献
6.
This article presents a comprehensive many-body theory for
optically excited semiconductors. The coupled equations
of motion for the correlation functions of the
Coulomb-interacting electron-hole system are derived
and solved for different excitation conditions. The generation of a
coherent excitonic polarization and its conversion into
incoherent populations is analyzed.
The spontaneous emission properties of the excited
system are evaluated using a fully quantized theory.
Luminescence from excitonic and electron-hole plasma
populations is computed, and significant hole burning in
the exciton center of mass distributions is predicted.
It is shown how different
excitations states of the many-body system
can be identified by their
characteristic signatures in the absorption spectra of a terahertz probe field. 相似文献
7.
The physical and mathematical approximations underlying the intranuclear cascade model (INC) algorithm are considered here. The INC algorithm is shown to be a version of Monte-Carlo calculations for multiple integrals which provide the solutions of the system of coupled equations for many-body distribution functions. The conditions under which these equations are derived from the Schrödinger many-body equations are analysed, with special emphasis on the finite size of the nuclear system. 相似文献
8.
基于相对论有效原子实势(RECP)和密度泛函(B3LYP/SDD)方法,优化得到了LiH,LiO和LiOH的分子结构;研究得到了LiH和LiO的Murrell-Sorbie分析势能函数以及LiOH的多体项展式分析势能函数,由势能函数导出了LiH,LiO和LiOH的离解能,分别为2.722eV,3.592eV和9.085eV,与实验值基本一致.在分析势能函数基础上,用准经典分子散射理论方法,研究了LiH与O的分子反应动力学.结果表明,碰撞反应是一个无阈能反应,即较低的初始平动能更有利于反应产物的形成,主要生
关键词:
LiH
LiOH
势能函数
分子反应动力学 相似文献
9.
P. J. Forrester 《Journal of statistical physics》1993,72(1-2):39-50
In a previous paper the two-particle distribution function and one-particle density matrix for the quantum many-body system with the 1/r
2 pair potential have been expressed as limiting cases of Selberg correlation integrals. Recurrence equations are derived which allow rapid evaluation of these multidimensional integrals. The exact results for the two-particle distribution are compared with the harmonic approximation. 相似文献
10.
The utility of projection operator formalisms for describing the dynamics of many-body systems is studied, and the compatibility of these formalisms with certain approximation schemes is evaluated in the light of known behavior of such systems. For simplicity the investigation is limited to the study of Brownian motion. Specifically, a memory kernel formalism and a kinetic equation formalism are compared for the calculation of the time evolution of the momentum autocorrelation function. Both perturbation expansions and averaged propagator approximations are investigated. The results from these studies suggest that the long-time behavior of the momentum autocorrelation function is sensitive to the long-range nature of the interparticle potential.This work was supported in part by the National Science Foundation under Grant GK-19360X. 相似文献
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P. I. Bezotosnyi K. A. Dmitrieva S. Yu. Gavrilkin K. S. Pervakov A. Yu. Tsvetkov V. P. Martovitski A. G. Rybkin O. Yu. Vilkov V. M. Pudalov 《JETP Letters》2017,105(8):514-518
A change in the time dependence of the second moment of the distribution of intensities of coherences with various orders in the spectrum of multiple-quantum NMR in a solid at the inclusion of an inhomogeneous magnetic field in the effective interaction is studied. Both the secular dipole–dipole and nonspecular twoquantum interactions are considered as nucleus–nucleus interactions, which correspond to traditional experimental realizations. It is shown that, with an increase in the magnitude of the inhomogeneous field, an exponential increase in the second moment of multiple-quantum NMR with time changes to a power-law increase. The results obtained in this work indicate that this second moment, which determines the average number of dynamically correlated spins, can be used as a convenient characteristic for studying a transition to a many-body localized state. 相似文献
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A molecular dynamic method is used to simulate the film growth process of Fe or Co clusters depositing on Cu substrate with low energy. The tight-binding (TB-SMA) many-body potential is used to simulate the interaction between atoms. The effects of different incident energies and/or substrate temperatures on the surface roughness, layer coverage function, radial distribution function (RDF), and residual stress are investigated. From the simulation results, as the substrate temperature and/or incident energy is increased, the surface roughness of the grown film could be reduced, and the interface intermixing is increased. Also, as compared to Co–Cu system, Fe–Cu system has better surface roughness, less interface intermixing, and similar radial distribution function as well as average stresses. 相似文献
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在相对论多体微扰理论和屏蔽理论的基础上,本文提出了一种计算等电子序列离子基组态能量的新方法,通过引入一个与核电荷数Z相关的能量修正函数γ(Z)来考虑由于忽略能量的高阶项对原子体系基组态能量的影响。在对类Li(Z=3~50)和类Be(Z=4~50)等电子序列离子的基组态能量所进行的理论计算研究结果表明,Z相关能量修正对于原子体系基组态能量的准确计算是有效的。 相似文献
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We analyze a new type of response function which portrays the properties of a system perturbed by an external field in terms of the perturbed two-point correlations of density fluctuations rather than in terms of perturbed averages of physical quantities. This response function of the second kind satisfies both fluctuation-dissipation-like theorems, relating it to three-point equilibrium functions, and hierarchical relationship linking it to conventional quadratic (rather than linear) response functions. In the equal-time limit, when the two density fluctuations are observed at the same time, the response function of the second kind is intimately connected to the two-particle correlation function of kinetic theory. This linkage opens an avenue for developing novel approximation techniques for correlated many-body systems. 相似文献
20.
In this work, we consider a quantum strongly correlated network described by an Anderson s - d mixing model. By introducing the Green function on the projected formalism of the Schrieffer and Wolf transformation, the
energy spectrum of the system can be obtained. Using this result we calculate the survivability distribution of the network
and discuss the local magnetism in the network, which shows that the survivability is an important statistical characteristic
quantity not just to reflect the network topological property but also dynamics.
相似文献