共查询到20条相似文献,搜索用时 10 毫秒
1.
2.
A generalization of perturbational studies of the Anderson model to the case of finite Coulomb repulsionU between the localized electrons is presented. We evaluate one particle spectra for the impurity and the lattice case. When varyingU, systematic trends in the peak positions and in the dynamic energy scale are obtained, which agree well with intuitive expectations. The results provide an understanding of the Anderson model in the full range of its parameters to the same extent as was previously furnished by the NCA approach to theU= case.This work was performed within the research program of SFB 252 Elektronisch hochkorrelierte metallische Materialien 相似文献
3.
A relativistic particle in an attractive Coulomb field as well as a static and spherically symmetric gravitational field is
studied. The gravitational field is treated perturbatively and the energy levels are obtained for both spin 0 (Klein-Gordon)
and spin 1/2 (Dirac) particles. The results are shown to coincide with each other as well as the result of the nonrelativistic
(Schr?dinger) equation in the nonrelativistic limit. 相似文献
4.
The generalized Trotter formula is used to map the two-dimensional spin-1/2 XY model onto several three-dimensional Ising models with complicated many-spin interactions. This hierarchy of Ising-like models is studied by means of analytic and Monte Carlo techniques. We demonstrate that the sequence of these Ising models can be used to calculate accurately the thermodynamics of the two-dimensional spin-1/2 XY model. By calculating the specific heat, spin correlation functions, susceptibilities and a disorder parameter, we address the question of the nature of the phase transition in the two-dimensional spin-1/2 XY model. 相似文献
5.
We show that thermodynamic properties can be used to determine whether, the degradation in Tc with increasing disorder observed in some A-15 compounds, is due to a reduction in electronic density of states and/or electron-phonon interaction or is due instead to an increase in Coulomb repulsion coming from increased localization as suggested by Anderson et al. 相似文献
6.
7.
Joseph Slawny 《Journal of statistical physics》2009,135(4):639-650
Most general self-dual spin 1/2 models in any dimension, with interaction that is translation-invariant in a suitable sense
(‘transitive models’), are determined. In the process of classification of such systems, a class of models which are self-dual
in a particularly strong sense is introduced. 相似文献
8.
9.
Jens Bolte 《Foundations of Physics》2001,31(2):423-444
For relativistic particles with spin 1/2, which are described by the Dirac equation, a semiclassical trace formula is introduced that incorporates expectation values of observables in eigenstates of the Dirac-Hamiltonian. Furthermore, the semiclassical limit of an average of expectation values is expressed in terms of a classical average of the corresponding classical observable. 相似文献
10.
11.
G. Benenti X. Waintal J.-L. Pichard D.L. Shepelyansky 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(3):515-521
Using Hartree-Fock orbitals with residual Coulomb repulsion, we study spinless fermions in a two-dimensional random potential.
When we increase the system size L at fixed particle density, the size dependence of the average inverse compressibility exhibits a smooth crossover from a
1/L
2 towards a 1/L decay when the Coulomb energy to Fermi energy ratio increases from 0 to 3. In contrast, the distribution of the first energy excitation displays a sharp Poisson-Wigner-like
transition at .
Received 13 March 2000 相似文献
12.
V. V. Semenikhina A. G. Lyalin A. V. Solov’yov W. Greiner 《Journal of Experimental and Theoretical Physics》2008,106(4):678-689
A method for calculating the characteristics of the stability, energy, and geometry of an atomic cluster at a solid surface is proposed, which is based on a droplet model that takes into account the cluster-solid interaction. As an example, the interaction of a neutral argon cluster with a (001) surface of graphite is considered. The results of calculations performed within the framework of the droplet model show good agreement with the results of numerical simulation based on a dynamic search for the most stable isomers in the course of cluster growth. It is shown that the droplet model can be used for simple evaluation of the geometry, stability, and energy characteristics of clusters at solid surfaces. 相似文献
13.
We prove the Hawking effect, for a gravitational collapse of charged star in the case of a charged massive Dirac field. 相似文献
14.
15.
D.L. Huber 《Physica B: Condensed Matter》2012,407(21):4274-4276
In this paper, we investigate spin diffusion in Heisenberg chains with uniaxial nearest-neighbor interactions. The approach followed is based on an analysis of the infinite-temperature longitudinal spin density and spin current correlation functions. For S=1/2, exact results are presented for the time-dependent correlation functions in the XY limit. Away from this limit, the second and fourth moments of the Fourier transform of the spin density correlation function provide information about spin dynamics for arbitrary values of the spin. The moments are used in an assessment of the accuracy of the Gaussian approximation for the spin diffusion constant for S=1/2. The general behavior of the Gaussian approximation when S>1/2 is discussed, and numerical results for the spin diffusion constant are presented for S=1/2, 1, 3/2, 2 and in the classical limit. A moment-based criterion for the boundary in reciprocal space between diffusive and non-diffusive dynamics that applies to arbitrary values of the spin is presented. 相似文献
16.
The problem of the Coulomb explosion of a homogeneous cluster with light and heavy ions has been analytically solved. The space-time and spectral distributions of accelerated ions have been obtained. The characteristics of scattered light ions are determined as functions of the atomic composition of the cluster. It has been shown that sources of monoenergetic ions can be created using the interaction of high-power ultrashort laser pulses with molecular clusters. 相似文献
17.
18.
We consider mesoscopic fluctuations of Coulomb drag transresistivity between two layers at a Landau level filling factor nu = 1/2 each. We find that, at low temperatures, sample to sample fluctuations exceed both the ensemble average and the corresponding fluctuations at B = 0. At the experimentally relevant temperatures, the variance of the transresistivity is proportional to T(-1/2). We find the dependence of this variance on density and magnetic field to reflect the attachment of two flux quanta to each electron. 相似文献
19.
Vibrationally resolved photoelectron spectra were obtained for cold C(70)- and C(70)2-. Accurate values for the first and second electron affinities (EA's) of C(70) were measured as 2.765 +/- 0.010 and 0.002 (+0.01/-0.03)eV, respectively, establishing that C(70)-2 is an electronically stable dianion in the gas phase. The difference between the first and second EA (2.75 eV) provides a direct experimental measure for the on-site Coulomb and exchange interactions between the two excess electrons in C(70)-2. Strong electron correlation effects were also observed between the two excess electrons in C(70)-2. 相似文献
20.
We present a new application of the traditional thermodynamic Bethe ansatz to the spin-1/2 antiferromagnetic uniform Heisenberg chain and derive exact nonlinear integral equations for just two functions describing the elementary excitations. By using this approach, the magnetic susceptibility chi and specific heat C versus temperature T are calculated to high accuracy for 5x10(-25)=T/J=5. The chi(T) data agree very well at low T with the asymptotically exact theoretical low- T prediction of Lukyanov [Nucl. Phys. B522, 533 (1998)]. The unknown coefficients of the second and third lowest-order logarithmic correction terms in Lukyanov's theory for C(T) are estimated from the C(T) data. 相似文献