Electronic charge density of aluminum

The valence electronic charge density is calculated for aluminum from wave-functions obtained via Ashcroft's pseudopotential. A contour plot of the charge density is presented in the (100) plane. The Fourier transform of the charge density is used to calculate the atomic form factors which are compared with experimental X-ray form factors. The accuracy of the wavefunctions are further tested by comparing calculations of the imaginary part of the frequency dependent dielectric function with and without the effect of core states.     

Experimental nuclear charge density and theoretical description of the above-barrier light heavy-ion fusion process

Theoretical modeling of nucleus-nucleus collisions is often based on the nucleus-nucleus potential.One of the advanced methods for constructing this potential is the semi-microscopical double-folding model with M3 YParis NN-forces.Proton and neutron densities are significant components of this model.The correct nucleon density(ND) must reproduce the experimental nuclear charge density(NCD).However,those who deal with modeling the fusion process typically disregard this circumstance.We aim to ach...     

Experimental and theoretical study of charge transfer in hydrogen ion scattering from a graphite surface

Ion scattering spectrometry (ISS) with time of flight (TOF) analysis is employed to measure the ion fraction of positively charged hydrogen (H⁺) projectiles scattered from a well characterized highly oriented pyrolitc graphite (HOPG) surface at a 45° scattering angle, various ingoing/outgoing angles and two different incoming energies (4 and 5 keV). In the theoretical approach, the negative ionization probability is calculated by employing a Green's function formalism to solve the dynamic collisional process. Both theoretical and experimental results are analyzed and contrasted. The theoretical negative ion fraction evolution during the collisional process is described in detail.     

激光作用铝靶爆轰波流场观测与理论分析

进行了强激光作用铝靶实验,采用纹影照相法,观察爆轰波流场演化过程,分析了爆轰波衰减规律。根据冲击波运动的自相似性,采用点爆炸模型描述了激光作用下爆轰波流场的演化,计算了波阵面速度、压力和温度。结果显示：爆轰波阵面沿迎着激光光源方向较快传播,波阵面形状由最初的半椭球形逐渐向半球形转变,在演化过程中扰动区结构复杂,存在多个密度间断层。在爆轰波开始传播阶段,波阵面的压力和温度较高但下降很快。     

激光作用铝靶爆轰波流场观测与理论分析

进行了强激光作用铝靶实验,采用纹影照相法,观察爆轰波流场演化过程,分析了爆轰波衰减规律。根据冲击波运动的自相似性,采用点爆炸模型描述了激光作用下爆轰波流场的演化,计算了波阵面速度、压力和温度。结果显示:爆轰波阵面沿迎着激光光源方向较快传播,波阵面形状由最初的半椭球形逐渐向半球形转变,在演化过程中扰动区结构复杂,存在多个密度间断层。在爆轰波开始传播阶段,波阵面的压力和温度较高但下降很快。     

长直带电导体柱的电场及其电荷面密度

通过保角变换法及其变换关系,求解长直带电导体柱的电场分及电荷面密度,利用数学软件MATLAB对其场分布进行数值模拟,并绘制出电荷面密度的分布曲线.     

Transportation of pinned charge density waves

We investigated the transport of pinned charge density waves (CDWs) that is observed in low dimensional materials. We treated pinned CDWs as moving CDWs that were confined within a typical quantum well amongst the many different types where pinning occurs at the barrier. We calculated the current flowing out of the quantum well by confined CDWs. The calculated conductivity is in good correspondence with experimental data in TTF–TCNQ, where the measured Fröhlich–Peierls temperature is 60 K much higher than the theoretical value of 20 K. The voltage dependence of the conductivity was calculated, where this is easily transformed into the dependence of electric field. The magnetic susceptibility was also calculated with a similar trend of experimental data. The susceptibility is a diamagnetic contribution by CDWs in addition to the constant background Pauli paramagnetic part.     

Spin and charge density changes in FeSn

Interpretation of the hyperfine field and isomer shift changes in terms of a spin and charge density changes is given for a series of Fe–Sn alloys. Linear correlations have been revealed for the following⁵⁷Fe site quantities: the hyperfine field H(0,0) and the isomer shift IS(0,0) of undisturbed neighbour configurations; the average hyperfine field, and the average isomer shift, ; the average hyperfine field and the average number of Sn atoms in the first two neighbour shells, . The latter correlation holds also for the Sn site measurements. From the first two correlations, the following hyperfine coupling constants have been evaluated: (a) for s-like itinerant electrons yielding 183 k0e/s-el., (b) average coupling constant yielding –319 k0e/s-el.. From the correlation between the Fe site and the change in the spin or charge density caused by one Sn atom for unit cell, has been deduced to be equal to 0.27 s-el./Sn-atom/u.c..     

Valence charge density in indium arsenide

Valence charge densities of zinc-blende structure InAs calculated using an ab initio pseudopotential method are reported. It is found that as zinc-blende structure InAs is compressed, the changes in the charge density are gradual even as the volume at which it is unstable in favour of a rock salt structure is passed, and that under pressure the bond charges tend to move away from the anion sites towards the bond center sites.     

Electronic charge density in simple metals

The valence electron density is calculated for aluminum, magnesium, and sodium using an OPW-based pseudopotential method. The Fourier transform of the charge density is used to calculate atomic form factors which compare very well with experimental X-ray scattering form factors. The non-local and energy-dependent nature of the pseudopotential and corrections from the orthogonalization hole are shown to be important.     

Contact charge density in metallic dysprosium

The contact conduction electron density in metallic dysprosium has been calculated following the APW formalism and taking into account the effects of correlation and spin-polarization. A comparison of this density with that obtained from the Mössbauer isomer shift measurement has been made. An estimate of Δ〈r ²〉, the change in mean square nuclear charge radius between the two levels involved in theγ transition, has been made and compared with those obtained by other workers.     

Combined experimental and theoretical study of small aluminum oxygen clusters

We report a combined experimental and computational investigation of small Al_nO_m species (n ≤20, m ≤ 12), produced in a laser vaporization cluster source. The oxygen content in the clusters was tuned by varying the oxygen concentration in the carrier gas. Ionization energies are bracketed using different ionizing photon energies in the energy range between 5.37 and 7.89 eV. Among the singly doped Al_nO species, Al₃O and Al₁₅O are found to have relatively low ionization energies, which can be related to the magic character of the corresponding cations. Peculiarly low ionization energies also are observed for specific oxygen rich species (m > 1), suggesting the formation of ionically bound subunits. The structures and ionization energies of singly doped Al_nO^0,+ (n = 1 - 7) clusters were determined using density functional theory (B3LYP/6-311+G(d)). Electronic supplementary material Supplementary Online Material     

Experimental determination of space charge density associated with flow electrification phenomenon: Application to power transformers

At the solid/liquid interface, a charge zone called the Electrical Double Layer (EDL) appears. It is constituted of two zones of opposite sign, one in the solid and another one in the liquid. When a liquid flows through a pipe, an axial streaming current is generated. This current is due to the convection of the charges coming from the electrical layer in the liquid. The experimental methods for the determination of space charge density have been clearly identified in the case of fully-developed EDL. On the contrary, there is a need for further exploration in the case of a non-fully developed EDL. The purpose of this paper is to calculate the fully developed space charge density at the wall by streaming electrification experiments which are conducted in the case of non-fully developed EDL. Moreover, it introduces a simplified procedure for the experimental determination of space charge density as a function of liquid flow velocity. This procedure can be conducted for the investigation of flow electrification phenomena in transformers with oil/metal configuration.     

Non-linear conductivity of one-dimensional charge density wave

A pure system with one-dimensional CDW placed in a homogeneous electric field is considered. Non-linear effects are found to appear due to motion of a soliton superstructure. The dependence of the differential conductivity on the electric field is calculated.     

Two-pion exchange charge density and its related problems

The two-pion exchange charge density operators are derived in the static approximation. Their contributions to the charge form factors of ³He and ³H are investigated with the use of simple wave functions and are found to be appreciable at high momentum transfer (3 to 5 fm^?1). It is also shown that the exchange charge density modifies the enhancement factor of the electric dipole sum rule by around 10%. The distinguishing feature between the isoscalar and isovector exchange charge densities is pointed out.     

Pseudogap and charge density waves in two dimensions

Using angle-resolved photoemission spectroscopy we demonstrate that a normal-state pseudogap exists above T(N-IC) in one of the most studied two-dimensional charge-density wave (CDW) dichalcogenides 2H-TaSe(2). The initial formation of the incommensurate CDW is confirmed as being driven by a conventional nesting instability, which is marked by a pseudogap. The magnitude, character, and anisotropy of the 2D-CDW pseudogap bear considerable resemblance to those seen in superconducting cuprates.