Self-consistent pseudopotential calculation for the (111) surface of aluminum

The electronic structure of the (111) surface of aluminum is calculated using self-consistent pseudopotentials. Surface states are identified and the (111) work function calculated. The behavior of the total charge density and potential near the surface is displayed and discussed. Self-consistency is found to be of crucial importance.     

Self-consistent calculation of the quadrupole-octupole deformation energy surface of 222Ra

The Hartree-Fock + BCS quadrupole-octupole deformation energy surface of ²²²Ra, calculated with the Skyrme SIII interaction, presents a minimum for a non-zero value of the octupole moment. Our results suggest the existence of a quadrupole coupling which may account for the observed differences between the moments of inertia of the positive- and negative-parity bands.     

Self-consistent calculation of the electron structure and X-ray spectra of chromium nitride

The energy band structure of cubic chromium nitride is calculated by the self-consistent method of associated plane waves for a broad energy range. Self-consistency led to overlapping of the p-band of nitrogen and the d-band of chromium and to the appearance of an energy discontinuity in the region of unbounded states. The total and local partial densities of the states are calculated. With allowance for the probability of transition, the K₅- and L₁₁₁-emission bands of chromium, the K-band of nitrogen, and the K-edge of absorption of chromium in chromium nitride are calculated in a dipole approximation. The possibility of calculating the absorption edge with allowance for the effect of shell holes is discussed. Statisfactory agreement is obtained with experimental data.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 72–78, August, 1985.     

A method of dopant electron energy spectrum parameterization for calculation of single-electron nanodevices

Solitary dopants in semiconductors and dielectrics that possess stable electron structures and interesting physical properties may be used as building blocks of quantum computers and sensor systems that operate based on new physical principles. This study proposes a phenomenological method of parameterization for a single-particle energy spectrum of dopant valence electrons in crystalline semiconductors and dielectrics that takes electron–electron interactions into account. It is proposed to take electron–electron interactions in the framework of the outer electron shell model into account. The proposed method is applied to construct the procedure for the determination of the effective dopant outer shell capacity and the method for calculation of the tunneling current in a single-electron device with one or several active dopants–charge centers.     

Self-consistent Hartree-Fock calculation of exchange effects in a weakly inhomogeneous electron gas

An exact calculation is given for the function B_x(n) which enters the Hohenberg-Kohn-Sham expansion, in powers of $\text{?n(}\text{r}\text{)}$, of the echange energy of an inhomogeneous eletron gas. The calculation is made for arbitrary inter-particle interaction. It is shown that the gradient expansion does not exist, in the case of Coulomb interaction, unless correlations are taken into account.     

Medium energy electron diffraction on aluminum

Measurements of the specular beam intensity in the medium range of energy (645 eV and 980 eV) are presented for the aluminum (001) and (110) surfaces. They have been performed with a LEED goniometer allowing to achieve high accuracy in the determination of the angular parameters of the diffraction experiment. The experimental results are displayed in the form of iso-intensity maps in (θ, φ) coordinates at a constant primary beam energy. θ denotes the colatitude angle of incidence and is varied in the range 30° to 80°. φ denotes the azimuth and is varied between 0° and 360°. Sections of the maps at constant angle of incidence are known as rotation diagrams. A model calculation ignoring intra-layer multiple scattering, but incorporating inter-layer multiple scattering processes shows the prominent role of the latter, in many cases, and the non-negligible contribution of the former in other cases. Sections of the maps at constant azimuth are called incidence-profiles. They are very sensitive to the azimuth and very hard to compute. Using the preceding model calculation, average incidence profiles have been computed, using as input parameters the refractive and absorptive potentials and the surface normal relaxation parameter obtained by a pseudo-kinematic analysis of experimental average incidence profiles as explained in another paper. The peak position and width have been compared to those obtained from the pseudo-kinematic calculation. From the result, it is shown that if averaging is performed according to a specific set of restrictive rules, the pseudokinematic analysis of the data has a semi-quantitative meaning.     

The electron energy spectrum of the alloy FeCo

The electron energy spectrum of the ordered alloy FeCo is analyzed by the Green's function method. The dependence of the spectrum on the electron configuration of the alloy components is investigated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 61–69, February, 1977.     

Self-consistent large-signal calculation on the gyrotron-TWA

By means of a ballistic method a self-consistent large-signal calculation on the gyrotron traveling wave amplifier (gyrotron-TWA) with uniform waveguide and magnetic field has been accomplished. The theory is valid for arbitrary harmonics of the cyclotron frequency and arbitrary TEmn modes.Computer simulation shows that under defined conditions a beam efficiency 50 %, an output power 300 kW and a gain28 dB at a central frequency of 35 GHz with a 3 dB bandwidth of 2,7 % could be obtained. This method will be effective for the theoretical analysis and the parameter-optimization on the gyrotron-TWA.     

Reflection electron energy loss spectroscopy of aluminum

Reflection electron energy loss spectra (REELS) of Al(111) single crystal and of the aluminum polycrystalline (poly Al) film were measured at 200 eV and 1000 eV electron energies for a variety of experimental geometries and were mutually compared. No anisotropy was found for the poly Al, as expected. Polar intensity plots evaluated from the elastic (no loss) and inelastic first surface plasmon- and first bulk plasmon-loss intensities of the Al(111) surface show clearly discernable peaks for both considered electron energies. Their positions on the angular axis are the same for the elastic as well as for the inelastic, surface and bulk plasmon-loss peaks. The polar plots of intensities of the elastically and inelastically reflected electrons were compared to calculated intensities of photoelectrons emitted from the Al 2s core level to the same kinetic energy. Peak positions in the theoretically determined polar plots of electron intensities agree with those obtained experimentally in REELS.     

金属铅电子结构和声子谱的第一性原理计算

采用LDA的平面波赝势和密度泛函微扰理论(DFPT)方法计算了铅的晶体结构,电子能带,声子能量,并与实验数据进行了详细的比对.通过对电子结构的分析,发现铅没有宏观磁矩表现,电子能带在费米面处存在相交,说明铅具有强的金属性.发现在高对称q点附近,声子结构的计算与实验数据符合很好,而在对称性较低的X点附近,计算结果偏大于实验数据,导致了声子态密度计算结果"频移"现象的发生.结果表明,采用LDA的平面波赝势方法和DFPT方法计算铅的电子结构和声子能量切实可行,计算结果可靠.     

Relativistic calculation of the energy spectrum of Zn-like highly charged ions

Perturbation theory together with a model zeroth-order approximation is used to calculate the energy levels of the 4s4p, 4p², 4s4d, 4p4d, and 4s5s configurations of a number of Zn-like ions with nuclear charges in the range Z = 36–50. The zeroth-order functions of the approximation are the wavefunctions of an electron that moves in the field of the model core potential. The parameters of the model potential are found by using the empirical energy levels of the Cu like ions. The calculation is carried out to first order in the perturbation theory together with the inclusion of an effective account of the higher order corrections. The calculation is accurate to a fraction of a percent.Deceased.Translated from Izvestiya Vysshikh Uchebnyh Zavedenii, Fizika, No. 10, pp. 99–105, October, 1985.The authors thank K. G. Oganov for help in carrying out the numerical work.     

Self-consistent calculation of electron density and muon hyperfine field in transition metals and their compounds

The use of finite cluster models to represent the electronic structure of solids in the framework of self-consistent local density theory is reviewed. The embedding problem is discussed, and practical variational approaches to treating crystalline potentials and wavefunction boundary conditions are presented. Hyperfine fields at ⁺ sites in Fe, Ni, and Co are found to result from a delicate balance between negative contributions of deep-lying (bound, paired) states and positive contributions due to polarization of band levels near the Fermi energy. The nature of muon screening, and the potential for ⁺ in Cu and Al are briefly considered. Finally, we explore the likely binding sites and bonding mechanisms for ⁺ in the defect compound VO _x .     

On the electron energy spectrum in heavily doped non-parabolic semiconductors

An attempt is made to present a simple theoretical analysis of the energy-wave vector dispersion relation of the conduction electrons in heavily doped non-parabolic semiconductors forming band tails. We observe that the complex energy spectrum in doped small-gap materials whose unperturbed conduction band is described by the three band model of Kane is due to the interaction of the impurity atoms in the tail with the spin-orbit splitting constant of the valence band (Δ), For band-gap (E_g)<Δ the imaginary part predominates which tails in to the conduction band. For the opposite inequality the real part comes in to play which tails in to the split-off band. In the absence of the band tailing effect, the imaginary part of the complex energy spectrum vanishes and the same is also true for doped two-band Kane-type and parabolic energy bands respectively. The present formulation helps us in investigating the Boltzmann transport equation dependent transport properties of degenerate semiconductors and are expected to agree better with experiments. The well-known results of unperturbed three and two band models of Kane together with wide-gap parabolic energy bands have been obtained as special cases of our generalized analysis under certain limiting conditions.     

飞秒激光与等离子体相互作用过程中超热电子能谱的测量

 报道了在3TW飞秒激光器上完成的激光 等离子体相互作用过程中产生的超热电子的能谱测量结果。能谱测量显示：在较低的能段，超热电子能谱先是呈现一个局部的平台，然后迅速衰减，呈现非类麦克斯韦分布，这是由于几种加热机制共同作用，其中占主导地位的是反射激光对电子的加速；在较高的能段，超热电子能谱呈类麦克斯韦分布，拟合的温度远远高于已知的温度定标律给出的温度，其原因在于超热电子分布的高能尾部本身的抬高和激光的自聚焦及成道。