共查询到20条相似文献,搜索用时 359 毫秒
1.
An analytical approach for simultaneously determining an inelastic mean free path (IMFP), a surface excitation parameter (SEP) and a differential SEP (DSEP) with absolute units was applied for the analysis of absolutely measured reflection electron energy loss spectra for Au. The IMFP, SEP and DSEP in Au for 300-3000 eV electrons are successfully obtained. The obtained DSEPs show a reasonable agreement with those theoretically calculated. The present SEPs were compared with those calculated by several empirical equations, revealing that the present SEPs are close to those calculated using the Oswald's equation. The IMFPs for Au determined by the present analysis were compared with those calculated by the TPP-2M predictive equation, revealing that the present IMFPs are in fairly good agreement with those calculated by the TPP-2M equation. The results confirmed that the present approach is effective for experimentally determining the SEP, DSEP, and IMFP for electrons in solids. 相似文献
2.
The first two quantum corrections to the second virial coefficients of the Smith-Thakkar potential are calculated. Parameters for neon and helium, gases in which quantum effects are important, are then determined by fitting to semiempirical dispersion coefficients and experimental second virial coefficients. Viscosity coefficients for both gases and vibrational energy level spacings for the neon dimer are calculated as independent tests of the potentials. Overall agreement with experiment is excellent for neon and moderate for helium. The previously determined parameters for argon are found to be only very slightly perturbed by the inclusion of quantum corrections in the calculated second virial coefficients. 相似文献
3.
Amos Harpaz 《Foundations of Physics》2007,37(4-5):763-772
The potential of a static electric charge located in a Schwarzschild gravitational field is given by Linet. The expressions
for the field lines derived from this potential are calculated by numerical integration and drawn for different locations
of the static charge in the gravitational field. The field lines calculated for a charge located very close to the central
mass can be compared to those calculated by Hanni–Ruffini. Maxwell equations are used to analyze the dynamics of the falling
electric field in a gravitational field. 相似文献
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We present a simplified relativistic configuration interaction method (SRCI), by which all the energy levels and oscillator strengths in each transition array can be calculated. There exist generalized quasi-sum relations for the calculated oscillator strengths in the relevant transition arrays by the SRCI and by an unresolved transition array model (UTA). Based on UTA and the detailed configuration accounting (DCA), with a fully relativistic treatment incorporated with the quantum defect theory, the X-ray absorption spectra for any middle- and high-Z plasmas or composite plasmas can be calculated with much less computational efforts. The gross features of calculated spectra by DCA-UTA are in agreement with the relevant experimental measurements, except some detailed structures in some narrow spectral ranges. Such detailed structures can be calculated by SRCI incorporated with DCA-UTA. As an illustrative example, the absorption spectra of Ge plasmas are calculated by DCA-UTA-SRCI and are in agreement with the experimental opacity data. Therefore, the theoretical method (DCA-UTA-SRCI) verified by experimental measurements will not only be a basic tool to provide “precision” opacity data for the inertial confinement fusion research (ICF) and studies in stellar physics but also can be used to analyze the relevant diagnostic measurements for ICF plasmas. 相似文献
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用全实加关联方法计算了类锂原子体系(Z=21~30)偶极跃迁1s22s -1s23p的跃迁能、振子强度以及1s23p态的精细结构劈裂.非相对论能量用Rayleigh -Ritz变分法确定;相对论修正和质量极化效应用微扰论计算;同时考虑了来自量子电动力学(QED)效应的修正.得到的理论结果与实验数据及物理规律符合的很好. 相似文献
7.
Hyperfine interaction constants (HFICs) of dangling bonds for CN and SiN films were calculated by density-functional theory. The averaged 14N isotropic HFICs for C dangling bonds are almost equal to those for Si dangling bonds. The anisotropic 14N HFICs calculated for C dangling bonds are larger than those for Si dangling bonds by a factor 2. The calculated results were compared with experimental results obtained by electron spin resonance and electron nuclear double resonance. It was indicated that the carbon dangling bonds are located such that they avoid N atoms in CN films. 相似文献
8.
Hu Chi 《International Journal of Infrared and Millimeter Waves》2003,24(11):1999-2006
Semicircular groove guide is a kind of waveguide for millimeter waves. In this paper, a conformal mapping technique is used to analyze it. Several semicircular groove guides are calculated with the method. It is shown that their cutoff wavelength calculated by the method are very close to those calculated by the transverse resonance method. 相似文献
9.
L. Farkas 《Czechoslovak Journal of Physics》1982,32(1):22-29
Based on the recently proposed Vosko-Wilk-Nusair interpolation formulae for the correlation energy density of the spin-polarized homogeneous electron liquid, a new parametrized form for the correlation potential for the self-consistent local-spin-density calculations of atoms, molecules and solids is proposed. The total energies and first ionization potentials for a few light atoms are calculated. The influence of the improved spin-polarization dependence on the calculated quantities is investigated, too. The calculated ionization potentials are in good agreement with observed values and are better (in average by 0.3 eV) than the values predicted by the hitherto most commonly used correlation potentials within the local spin density approximation. 相似文献
10.
Two-particle states of 18O and 42Ca are calculated within the shell model. The nuclear cores are represented by Woods-Saxon potentials, and for the residual interaction, central forces of Yukawa and Gaussian types are used. The wave functions for the low-lying states except for the O2+ and 22+ states in 42Ca are obtained, and the calculated energy spectra are in good agreement with experiments. Also E2 transitions are calculated and compared with experimental results. 相似文献
11.
An analysis method for atomistic cluster porosity is presented. Porosity and pore radii are calculated from the coordinates of atoms and van der Waals radii. The pore volume is calculated as the maximum volume of a sphere inscribed in a pore. The method is applied to a silicon dioxide thin film prepared by simulation of ion-beam sputtering. The porosity and distribution of pores by radius are calculated. The concentration of pores that are able to contain small molecules is estimated. 相似文献
12.
采取用理论计算的NOESY峰强度代替NOESY谱中重叠的对角峰或交叉峰强度,用理论计算值和实验数据相结合的方法解决峰强度矩阵的完整化问题,用全弛豫矩阵分析法定量分析了谱中有部分峰重叠的天然有机化合物冬凌草乙素的相敏NOESY谱,计算出冬凌草乙素分子中各质子间的交叉弛豫速率,根据1/rij6∝σij计算出相应的质子间距离,结果表明:用全弛豫矩阵分析法计算出的质子间距与分子力学计算得到的质子间距离完全一致。该方法能够用于谱中有部分峰重叠的天然有机化合物的NOESY谱的定量处理,可以为核磁共振方法确定分子在溶液中的三维空间结构提供可靠的结构参数 相似文献
13.
Electron impact ionization cross sections of Ne, Ar, Kr, and Xe atoms are numerically calculated. The electron perturbation
in the continuous spectrum in the target field is taken into account. The matrix elements are calculated in many-electron,
nonrelativistic approximation with allowance for the superposition of configurations and relaxation effect. The radial part
of the electron wave function in the continuum is calculated by solving the single-configuration Hartree-Fock equation. The
wave functions of electrons in the continuum are orthogonalized with respect to the core orbital functions. The calculated
cross sections are compared to the experimental data and calculations made using the plane-wave Born approximation and that
involving generalized oscillator strengths. 相似文献
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黄时中 《原子与分子物理学报》2016,33(6)
以最弱受约束电子势模型(WBEPM)理论为基础,建立了计算氦原子多极动态极化率和相互作用色散系数的稳定变分方法.导出了该方法中所涉及的矩阵元和线性方程组的解析表达式.作为应用,具体计算了基态氦原子的极化率和两体色散系数,将计算结果与用其他方法所得到的结果进行了比较, 数据基本一致. 相似文献
18.
以最弱受约束电子势模型(WBEPM)理论为基础,建立了计算氦原子多极动态极化率和相互作用色散系数的稳定变分方法 .导出了该方法中所涉及的矩阵元和线性方程组的解析表达式.作为应用,具体计算了基态氦原子的极化率和两体色散系数,将计算结果与用其他方法所得到的结果进行了比较,数据基本一致. 相似文献
19.
V. A. Zilitis 《Optics and Spectroscopy》2006,101(5):661-665
The photoionization cross sections for the ground and some excited states of 11 ions of the rubidium isoelectronic sequence from Rb through Ag10+ are calculated by the relativistic Dirac-Fock self-consistent field method. The energy dependence of the photoionization cross sections and the changes in the threshold values along the isoelectronic sequence are considered. The influence of the exchange effect and the choice of gauge on the calculated values of photoionization cross sections is examined. For practical use, the calculated cross sections are approximated by an analytical expression. Along with the total photoionization cross sections, the asymmetry parameter in the angular distribution of photoelectrons and the degree of their polarization are also calculated. 相似文献
20.
O. Johnson 《Journal of Physics and Chemistry of Solids》1981,42(2):65-76
The changes in electronic structure around each metal atom in an alloy are more accurately described in terms of electron redistribution than electron transfer. The important elements in a model for such electron redistribution are the electron configuration and radius of the positive ion cores and the conduction electron density and its variation in the interstitial regions. Positive ion core radii for metals are derived from an empirical relation between ion core radii and intermetallic distance with electronic configurations of the core from positron annihilation data. These derived ion core radii are in good agreement with those calculated for metal electron densities by Welch and Lynn from Hartree-Fock wave functions. Average conduction electron densities can be directly calculated from these radii and the experimental atomic volume; the variation of conduction electron density in the interstitial region is calculated by assigning electrons to octahedral and tetrahedral interstices according to the Interstitial Electron Model. The calculated electron densities and the interstitial variation agree very well with the experimental electron densities of Be as determined from X-ray diffraction data as well as with calculated electron densities for Na, Mg and Al. Ion core configurations are compared with those derived from band theory and also those of the Engle-Brewer Correlation and the Samsonov-Pryadkov-Pryadkov Configurational Model. 相似文献