Photoionisation cross-section calculations for satellite processes: Relaxed Hartree—Fock theory with application to helium n = 2 lines

1983 ◽  
Vol 32 (3) ◽  
pp. 193-203 ◽  
Author(s):  
J.A. Richards ◽  
F.P. Larkins
Keyword(s):  
Cross Section ◽  
Hartree Fock

(e, 2 e)-Spectroscopy and the Electronic Structure of Molecules. A Short Review with Selected Examples

1993 ◽  
Vol 48 (1-2) ◽  
pp. 358-370
Author(s):  
M. A. Coplan ◽  
J. H. Moore ◽  
J. A. Tossell
Keyword(s):  
Cross Section ◽  
Structure Factor ◽  
Impulse Approximation ◽  
Short Review ◽  
Hartree Fock ◽  
Structure Of Molecules ◽  
Kinematic Factor ◽  
Homonuclear Diatomic Molecule ◽  
Geometric Term ◽  
Inorganic Benzene

Abstract The simple plane wave target Hartree-Fock impulse approximation for the (e, 2e) reaction is developed. One result of the approximation is the separation of the expression for the (e, 2e) cross-section into a kinematic factor and a structure factor that contains all of the information about the target. When the target is a molecule, the structure factor can be further separated into atomic terms and a geometric term. This is illustrated for a simple one-electron homonuclear diatomic molecule. Three examples of the application of (e, 2e) spectroscopy to systems of chemical interest are given. They are borazine (inorganic benzene), the methyl siloxanes and the inorganic complex trimethylamine boron trifluoride.

Many-Electron Correlations in the Photoionization of a Nitrogen Atom

1974 ◽  
Vol 52 (4) ◽  
pp. 349-354 ◽  
Author(s):  
N. A. Cherepkov ◽  
L. V. Chernysheva ◽  
V. Radojević ◽  
I. Pavlin
Keyword(s):  
Nitrogen Atom ◽  
Cross Section ◽  
Cross Sections ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Electron Correlations ◽  
Sum Rule ◽  
Hartree Fock ◽  
The Cross ◽  
Good Agreement

Photoionization cross sections for the outer shell of the nitrogen atom ground state are calculated in the single-particle Hartree–Fock approximation and, in order to take into account many-electron correlations, also in the Random Phase Approximation with Exchange (RPAE). To be able to apply the RPAE, its modification for the half-filled shell atom, such as nitrogen atom, is presented. Calculation of length and velocity forms of the cross section in both approximations are compared with the available experimental data, and a good agreement is obtained. It has been found that in the RPAE the influence of many-electron correlations in a nitrogen atom is not great, but it is very important since, in contrast to the Hartree–Fock approximation, it results in the validity of the sum rule and the coincidence of the length and velocity forms of the cross sections, in agreement with the requirement of the general theory. The angular distribution of photoelectrons is also calculated in the RPAE, which has not been measured so far.

ON THE t(d, n)α REACTIVITY IN FUSION REACTORS

1989 ◽  
Vol 04 (22) ◽  
pp. 2101-2112 ◽  
Author(s):  
K. LANGANKE ◽  
C. ROLFS
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Thermal Equilibrium ◽  
Electron Screening ◽  
Fusion Reactors ◽  
Cross Section Data ◽  
Fermi Model ◽  
Thomas Fermi ◽  
Hartree Fock ◽  
Section Data

We argue that the most accurate t(d, n)α cross section data obtained by the Los Alamos group are enhanced at energies smaller than Ecm≈16 keV due to screening effects caused by the electrons present in the target. We show that these data in the energy range Ecm=16–70 keV can be well reproduced by a single Breit-Wigner resonance formula which, however, disagrees with the data at lower energies. Consistently the observed deviations can be associated with electron screening effects where the latter are estimated within the Thomas-Fermi model or a static Hartree-Fock approach. Adopting the present Breit-Wigner fit to the data at Ecm≥16 keV , we have calculated the reactivity of a d+t plasma at thermal equilibrium in the temperature range kT<10 keV as it might be important for future fusion reactors.

scholarly journals Electron scattering cross-sections for particle transport modeling in a weakly ionized air plasma

2021 ◽  
Vol 51 ◽  
pp. 96-111
Author(s):  
Vasily Sergeevich Zakharov ◽  
Mikhail Evgenievich Zhukovskiy ◽  
Sergey Vasilievich Zakharov ◽  
Mikhail Borisovich Markov
Keyword(s):  
Elastic Scattering ◽  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Electron Interaction ◽  
Inelastic Electron ◽  
Neutral Atoms ◽  
Hartree Fock ◽  
Wide Range ◽  
The Cross

Data on processes of electron scattering on ions and neutral atoms are required in fundamental studies and in applied research in such fields as astro- and laser physics, low density plasma simulations, kinetic modeling etc. Experimental and computational data on elastic and inelastic electron scattering in a wide range of electron energies is available mostly for the electron interaction with neutral atoms, but are very limited for the scattering on ions, notably for elastic processes. In present work the calculational approaches for the cross-section computation of electron elastic and inelastic scattering on neutral atoms and ions are considered. The atomic and ion properties obtained in quantum-statistical Hartree-Fock-Slater model are used in the direct computation of electron elastic scattering and ionization cross-sections by a partial waves method, semiclassical and distorted-wave approximations. Calculated cross-sections for elastic scattering on nitrogen and oxygen atoms and ions, and electron ionisation cross-sections are compared with the available experimental data and widely used approximations and propose consistent results. Considering applicability of Hartree-Fock-Slater model in wide scope of temperatures and densities, such approach to the cross-section calculation can be used in a broad range of energies and ion charges.

PL SPECTRA AND QUANTUM CONFINEMENT ANALYSIS OF Ge NANOSTRUCTURE IN RAPID OXIDATION OF SiGe SUBSTRATE

2005 ◽  
Vol 19 (30) ◽  
pp. 1767-1774 ◽  
Author(s):  
WEIQI HUANG ◽  
SHIRONG LIU
Keyword(s):  
Cross Section ◽  
Quantum Confinement ◽  
Oxidation Behavior ◽  
Suitable Model ◽  
Nano Structure ◽  
Scanning Method ◽  
Pl Spectra ◽  
Hartree Fock ◽  
Layer Sample ◽  
First Time

The investigation on the oxidation behavior of Si 1-x Ge x alloys (x=0.05, 0.15 and 0.25) is carried out. It is found for the first time that on the oxide film a germanium nano-cap with a thickness of 1.8~2.8 nm and a few Ge nanoparticles with diameters ranging from 5.5 nm to 10 nm are formed by rapid oxidation of Si 1-x Ge x substrate. A new scanning method on the decline cross-section of the multiple layer sample is adapted to measure the layer thickness and the composition. Some new peaks in photoluminescence (PL) spectra are discovered, which could be related to the nano-cap and the nanoparticles of germanium. A suitable model and several new calculating formulas with the unrestricted Hartree–Fock–Roothaan (UHFR) method and quantum confinement analysis are proposed to interpret the PL spectra and the nano-structure mechanism in the oxide.

Discrepancy of in-medium nucleon–nucleon cross-section in different T-matrix representations

2014 ◽  
Vol 23 (04) ◽  
pp. 1450023 ◽  
Author(s):  
Yong-Zhong Xing ◽  
Xing-Wen Zhao
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Nucleon Nucleon ◽  
Matrix Representations ◽  
Proton Proton ◽  
Hartree Fock ◽  
Wave States ◽  
T Matrix ◽  
The Cross ◽  
Three Body

In this paper, we study the in-medium nucleon–nucleon (NN) cross-section by using the Dirac–Breuckner–Hartree–Fock approximation (DBHF) with T-matrix project technique for determining the nucleon self-energy. By solving Thompson equation for different partial-wave states separately, we find that the discrepancies of nucleon self-energies in various T-matrix project representations are dominated by the channels with smaller angular momentum. Although the cross-section is independent on the project of T-matrix, the medium suppression of the cross-section in various T-matrix representations are apparently different due to the self-consistency of DBHF calculation involving effect mass of nucleon as an iterative parameter. Our results also show that the cross-sections in the complete pseudovector (CPV) choices are larger than those obtained with both DBHF in the pseudoscalar (PS) choice and nonrelativistic Brueckner–Hartree–Fock with three-body force (BHF + 3BF), respectively. Further comparison shows that the neutron–proton (NP) cross-section within DBHF + PV approach, [Formula: see text], is approximately equal to and slightly larger than that evaluated with BHF + 3BF, [Formula: see text], while the neutron–neutron (NN) (or proton–proton (PP)) cross-section given by DBHF + PV method, [Formula: see text], being the closest to the cross-section calculated by using BHF without 3BF in the lower energy region. Additionally, the discrepancies of the in-medium nucleon–nucleon differential cross-section induced by different representations of T-matrix in DBHF are discussed for nuclear matter with different densities.

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