统计自洽场INFERNO模型中电子共振态

对Liberman的统计自洽场INFERNO模型中的电子共振态进行研究,计算金属铀在两个温度密度点处的电子共振态,给出共振能量区间内电子的态密度,波函数,相移因子随能量的变化及位相-振幅形式的波函数中的位相随能量的变化,得到与非相对论情况下完全一致的结果.     

Local state density and the reflectivity of electrons at a crystal surface

Local densities of electron states at and near the surface of a semi-infinite solid are discussed and compared with the corresponding ones in the infinite solid. The reflectivity coefficients for electrons, incident from both sides on the surface, are shown to be closely related to these densities. Illustrating results are given for the one-dimensional model crystal. The surface Green function (SGF) method is used.     

Parity dependence of nuclear level densities

A simple formula for the ratio of the number of odd- and even-parity states as a function of temperature is derived. This formula is used to calculate the ratio of level densities of opposite parities as a function of excitation energy. We test the formula with quantum Monte Carlo shell model calculations in the (pf+g(9/2)) shell. The formula describes well the transition from low excitation energies where a single parity dominates to high excitations where the two densities are equal.     

OsSi2电子结构和光学性质的研究

采用基于第一性原理的密度泛函理论赝势平面波方法,对正交相OsSi₂的电子结构、态密度和光学性质进行了理论计算,能带结构计算表明它是一种间接带隙半导体,禁带宽度为0813 eV;其价带主要由Os的5d和Si的3p态电子构成;导带主要由Si的3s,3p以及Os的5d态电子构成;静态介电常数ε₁（0）=1543; 折射率n＝393并利用计算的能带结构和态密度分析了OsSi₂的介电函数、吸收系数、折射率、反射率、 关键词： 2')" href="#">OsSi₂ 第一性原理 电子结构 光学性质     

Effect of the d-f correlation on the electronic structure of intermediate valence systems

The electronic structure of an intermediate valence system is calculated by means of a real space renormalization technique on a Bethe lattice. The d-f Coulomb repulsion G is treated into the alloy analogy approximation. The valence and the densities of states are calculated as a function of G. We find that the hybridization gap decreases when G increases, and that the density of states at the Fermi level exhibits a peak as a function of G.     

XPS valence bands of Ti,Zr, Nb,Mo and Hf

The XPS valence band spectra of polycrystalline Ti, Zr, Nb, Mo and Hf have been measured with a resolution of 0.6 eV. The spectra were compared with theoretical densities of states. Good agreement is achieved if the partial densities of states are considered and a many body line shape function and life time broadening are taken into account. The sigularity index determined at various core lines as well as the experimentally determined relative valence band cross sections are reported.     

Single-particle spectrum of the degenerate electron gas

Extensive numerical results in the Random Phase Approximation are presented for the spectral weight function, the momentum distribution, and the density of states of the degenerate electron gas over a range of metallic densities. The single-particle spectrum contains not only the damped quasiparticle but also structure due to plasmon effects. At low momenta there is a second elementary excitation of appreciable weight. The density of states has a satellite band at energies more than the plasma energy below the Fermi level. The results confirm the main features of an earlier analysis using a simplified dielectric function.     

Calculation of the He-Cd dc discharge

Numerical evaluations of the excited atom densities and the volt-ampere characteristics in He-Cd dc mixture discharge in a cylindrical tube are reported. For this purpose, under non-equilibrium conditions in low current and low pressure discharge, a set of coupled rate equations for the number densities of atoms in most important quantum states is solved. A model of Cd-and He-atom possessing six and four levels, respectively, is assumed. The results of the computation are given as a function of the external positive column parameters at relative cadmium concentration 10^–3.     

Theory of corner reflectors in electron waveguides

The transport properties of corner reflectors have been studied using a method derived from the embedding method for confined quantum systems. The method is used to calculate the eigenstates and Green function which are expanded in any convenient basis set and then used to calculate the transmission and reflection coefficients. The results for the reflectors are compared to the results for a right-angled corner and a circular corner. Current flow studies have been done to clarify the transmission results. The local density of states for the corners are calculated to study bound states and resonances. The reflectors have both one-dimensional and two-dimensional densities of states depending on the size of the reflector.     

Interactions of surface states of copper with transition metals and cesium

The pseudopotential augmented-plane-wave method was used to study the surface structure of thin copper films with monolayers of Co, Ni, and Cs. Local densities of electron states, distributions of charge densities in the layers, and electron energy spectra are analyzed. The effect of adsorbates on the electronic properties of the Cu(001) surface and work function are discussed. Satisfactory agreement with available experimental data has been obtained.     

THE RESEARCH OF ELECTRONIC PROPERTIES OF HYDROGENATED а-Si

We first used Bethe lattice method and coherent potential approximation method to calculate the densities of bulk and surface states for a-Si,a-Si:H. The ideal vacancies were also studied.The results agree with experiments and other works.Dihedral disorder contributes to the submerging of a peak and sp peak of the valence band.In hydrogenated case,extra structure appears in the spectrum of densities of surface states.Doped hydrogen affects the densities of bulk states in the gap in principle,but hydrogen is not important for densities of surface states in the gap.Finally,we obtained self-energies which are in good.agreement with the empirical results from experiments and other methods^[1].     

Theory of valley-splitting without effective-mass approximation

A new method for determining electron states in a crystal with an external potential is proposed. It is applied to the n-inversion layer of Si(001)/SiO₂. The electron densities of the states show oscillations due to the super- position of Bloch waves from different valleys. As a function of the position of the interface there is a continuous transition from states described within the effective-mass approximation of Sham and Nakayama to surface states in the band gap.     

Cl chemisorption on the Pd(001) surface: A self-consistent LCAO calculation of electronic structure

The total and partial densities of states and work functions for the clean Pd(001) surface and for a c(2×2) Cl overlayer on this surface are calculated using a self consistent Gaussian LCAO technique. The adlayer increases the work function of the clean surface by 0.8 eV and leads to a distinct split off feature in the total density of states. The band structure of the bands composing this feature are compared to the bands of the isolated Cl layer.     

Study of the spin polarization of unoccupied states near the Fermi level by spin-dependent near-edge absorption spectroscopy

Spin-dependent near-edge absorption spectroscopy is presented as a new method for studying the spin density of states near the Fermi level at the absorbing atom site. Using circularly polarized synchrotron radiation the spin-dependent inner-shell absorption coefficient is measured as a function of the photoelectron energy. The spin-dependent absorption profile is expected to reflect directly the spin-density distribution of the states populated in the absorption process. The spin densities of 3d-and 4f-elements in pure systems, ferromagnetic alloy and compounds, and 5d-impurities in Fe have been investigated. The results are compared with spin-resolved band-structure calculations for the ferromagnetic ground state.     

具有近程序的N元无序材料理论

本文发展了具有近程序的N元无序材料理论,以原子间的关联函数描写从偏析到形成N元化合物之间的各种无序组态。以此为基础,采用以Bethe晶格为边界条件的原子集团格林函数理论,在紧束缚近似下,提出了计算N元无序材料的电子态密度方法。作为例子,计算了不同配比和不同无序组态下的三元无序材料A_xB_yC_z (x+y+z=1)的电子态密度,计算结果十分敏感地依赖于原子间关联的程度。 关键词：     

Small atomic clusters on metal, semiconductor, and graphene: A model approach

The analytical expressions for the densities of states of adsorbed monomer, dimer, and trimer have been derived using the simplest models for the densities of states of metal, semiconductor, and single-sheet graphene. It has been shown that all specific features in the densities of states of small clusters are predominantly determined by the main peculiarities of the density of states of the substrate rather than by the adsorbed clusters themselves.     

Saha decrements and collisional-radiative recombination and ionization coefficients for a nonequilibrium oxygen plasma

Using a time-dependent approach, a collisional-radiative model is developed for an oxygen plasma. Effective recombination and ionization coefficients are calculated for two specific cases, optically thin and optically thick in bound-bound u.v. radiation. The steady-state population densities for neutral and ionic states are presented in terms of their deviations from Saha equilibrium predictions. These results show the approach of the plasma to a state of local thermodynamic equilibrium (LTE) as a function of electron temperature and density. The computations are for temperatures between 1.0 and 3.0 eV and electron densities between 10¹⁶ and 10¹⁹ cm^-3.     

Excitation of helium atoms in collisions with plasma electrons in an electric field

The rate constants are evaluated for excitation of helium atoms in metastable states by electron impact if ionized helium is located in an external electric field and is supported by it, such that a typical electron energy is small compared to the atomic excitation energy. Under these conditions, atomic excitation is determined both by the electron traveling in the space of electron energies toward the excitation threshold and by the subsequent atomic excitation, which is a self-consistent process because it leads to a sharp decrease in the energy distribution function of electrons, which in turn determines the excitation rate. The excitation rate constant is calculated for the regimes of low and high electron densities, and in the last case, it is small compared to the equilibrium rate constant where the Maxwell distribution function is realized including its tail. Quenching of metastable atomic states by electron impact results in excitation of higher excited states, rather than transition to the ground electron state for the electric field strengths under consideration. Therefore, at restricted electron number densities, the rate of emission of resonant photons of the wavelength 58 nm, which results from the transition from the 2¹ P state of the helium atom to the ground state, is close to the excitation rate of metastable atomic states. The efficiency of atomic excitation in ionized helium, i.e., the part of energy of an electric field injected in ionized helium that is spent on atomic excitation, is evaluated. The results exhibit the importance of electron kinetics for an ionized gas located in an electric field.     

Circular Rydberg States of Atomic Hydrogen in an ArbitraryMagnetic Field

We report a theoretical scheme using a B-spline basis set to improve the poor computational accuracy of circular Rydberg states of hydrogen atoms in the intermediate magnetic field. This scheme can produce high accuracy energy levels and valid for an arbitrary magnetic field. Energy levels of hydrogen are presented for circular Rydberg states with azimuthal quantum numbers |m| = 10--70 as a function of magnetic field strengths ranging from zero to2.35
ⅹ10⁹ T. The variation of spatial distributions of electron probability densities with magnetic field strengths is discussed and competition between Coulomb and magnetic interactions is illustrated.     

Particle clustering and Mott transitions in nuclear matter at finite temperature: (I). Method and general aspects

The thermodynamic state of nuclear matter as regards dependence on density and temperature is considered. Expressions for the association degree are derived describing the ratio of nuclear matter which is clustered to bound states. The problem of two nucleons imbedded in the surrounding nuclear matter is considered with the help of the Bethe-Goldstone equation for thermodynamic Green functions. The two-particle energy shift due to the effective nuclear matter hamiltonian is considered in a Hartree-Fock approximation, and a Mott density is obtained so that for densities of nuclear matter higher than the Mott density bound states cannot exist. With a simplified effective two-nucleon interaction the association degree is calculated as a function of the nucleon density and the temperature.