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2 edition of Positron-electron momentum densities in metals. found in the catalog.

Positron-electron momentum densities in metals.

J. H. Kaiser

Positron-electron momentum densities in metals.

by J. H. Kaiser

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Published by University of East Anglia in Norwich .
Written in English


Edition Notes

Thesis (Ph.D.), University of East Anglia, School of Mathematics and Physics, 1984.

ID Numbers
Open LibraryOL13809569M

Abstract. A scheme to calculate the electron momentum density in simple liquid metals, with the effect ofboth electron correlations and ionic potentials included, is given. This scheme is Cited by: 2. These electron densities provide detailed information that gives important insight into the fundamentals of molecular structure and a better understanding of chemical reactions. The results of electron density analysis are used in a variety of applied fields, such as pharmaceutical drug discovery and biotechnology.

The problem of determining a metal's Fermi surface from measurements of projections of the electron or electron/positron momentum densities, such as obtained by Compton Scattering or Angular. The influence of the positron distribution on the electron-positron (e-p) momentum densities (MDs) is studied in terms of the l (l = s, p, d, f) character of the initial electronic state. The effect of the positron is discussed for momenta in the extended and reduced zone scheme on the example of Al (simple metal), Cu (metal with almost filled Cited by: 1.

Get this from a library! Electron, spin and momentum densities and chemical reactivity. [Paul G Mezey; Beverly E Robertson;] -- The electron density of a nondegenerate ground state system determines essentially all physical properties of the system. This statement of the Hohenberg-Kohn theorem of Density Functional Theory. A new spectrometer for the study of energy-resolved momentum densities is described. The (e, 2e) spectrometer uses a symmetric configuration and uses incoming energies up to 50 keV.


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Positron-electron momentum densities in metals by J. H. Kaiser Download PDF EPUB FB2

Abstract. Among the methods available for the study of the electronic structure of solids, the investigation of the electron momentum density with the aid of low-energy positron annihilation takes a place of increasing by: Positron-electron momentum densities in metals Author: Kaiser, J.

ISNI: Awarding Body: University of East Anglia Current Institution: University of East Anglia Date of Award: Physics of metals Share: Terms and.

Positron Annihilation Momentum Density Radon Transform Electron Correlation Effect Compton Profile These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm : G.

Das. Positron Annihilation 1 PRINCETON UNIVERSITY Physics Department Advanced Laboratory POSITRON ANNIHILATION IN A METAL Introduction Certain radioactive isotopes decay by emitting positrons, and the positrons can be used to probe the structure of solid materials.

For example, you can investigate the momentum distribution of conduction electrons in a Size: 60KB. Momentum density measurements by positron annihilation in metals and alloys; Recent experiments with a multicounter two-dimensional angular correlation apparatus: Authors: Berko, S.; Mader, J.

Affiliation: AA(Brandeis University), AB(Brandeis University) Publication: Applied Physics, Volume 5, Issue 4, pp Publication Date: 01/ Origin: SPRINGER. Spherically averaged electron momentum densities Π(p) are constructed by the numerical Hartree–Fock method for all atoms from hydrogen (atomic number Z=1) to lawrencium (Z=) in their experimental ground states.

We find three different types of momentum densities spread across the periodic table in a very simple manner for the 98 atoms other than He, N, Mn, Ge, and by: The thermalization rate of positrons in metals is computed as a function of the electron density parameter r, for the entire range of metallic density 2 Cited by: cusp in the electron density at the positron site.

9– The cusp determines the enhancement factor and contributes to the positron-electron correlation energy. The results for the ho-mogeneous electron gas can be successfully applied in cal-culating positron annihilation rates for real solids with inho-mogeneous electron densities.

The technique of positron annihilation as applied to the study of momentum densities and Fermi surfaces is reviewed. The angular correlation of the two annihilation photons is directly related to the momentum distribution of the positron-electron system; breaks in this distribution reveal the size and shape of the Fermi by: path due to electron momentum transfer (scattering) resulting from high current densities (> A/cm2), often at higher temperatures.

In contrast, electrolytic electromigration is the movement of metal across a nonconductive path at lower temperatures (densities (>10−3 A/cm2) in the presence of moisture. The stability, electronic structure, and positron-electron pair momentum of body-centered-cubic (bcc) copper, which is metastable, are theoretically studied and are compared with those of stable.

@article{osti_, title = {[ital a]-axis-projected electron-positron-momentum density and positron-annihilation spectra in YBa[sub 2]Cu[sub 3]O[sub 7[minus][ital x]]}, author = {Pankaluoto, R and Bansil, A and Smedskjaer, L C and Mijnarends, P E}, abstractNote = {We present and discuss theoretical and experimental [ital a]-axis-projected two-dimensional angular correlation of annihilation.

Electron momentum-space densities of Li metal: A high-resolution Compton-scattering study W. Schu¨lke, G. Stutz, F. Wohlert, and A. Kaprolat Institute of Physics, University of Dortmund, D Dortmund, Germany ~Received 19 March. Directional Compton profiles~CP’s.

of Li metal were measured for 11 directions of the momentum transferCited by: The relative contribution of 3d electrons to the momentum densities for positron annihilation in the iron series transition metals are calculated, using the atomic Hartree-Fock-Slater orbitals.

A discussion is given of the observed systematics. The per electron contribution to the angular correlations is found to decrease with the filling up of the d by: 1.

The positron–electron momentum density ρ (p) is basically the annihilation probability of a specific electron and positron into a pair of photons, over the entire occupied electron states, with total momentum p (1) ρ (p) = const ⋅ ∑ n, k O c c | ∫ v ε (p) exp [− i p r] φ + (r) φ n, k (r) d r | 2 where ε (p) is the positron–electron enhancement by: 1.

Introduction to the Electron Theory of Metals The electron theory of metals describes how electrons are responsible for the bonding of metals and subsequent physical, chemical and transport properties.

This textbook gives a complete account of electron theory in both periodic and non-periodic metallic systems. For the positron wave functions the independent particle model has been used. Because of the strong positron–electron attraction and many-body correlation problem, it turns out that, in spite of these strong correlation’s, the momentum density is reasonably well described by the independent particle by: 2.

momentum eeltlectron momentum after scatt ittering is id d tind epend ent of the momentum before scattering. 2/ Probability of a collision occurring in a time interval dt is dt/ τ.

τis called the ‘scattering time’, or ‘momentum relaxation time’. 3/ τ is independent of the initial electron momentum & energy. ͑ a ͒ Electron band structure of Cu along the ͓ ͔ direction in momentum space. Only the bands contributing to the momentum density of annihilating electron-positron pairs are shown.

process in some pure metals are presented. Specifically, changes in the positron lifetimes and in the CDB positron-electron momentum distributions during vacancy clustering in pure Al, Cu, Mg and Nb were studied.

These metals were selected since vacancy-like defects play an important role in: (i). Electron momentum density in yttrium The Fermi surface of Y and positron-electron momentum distributions of Y were extracted but is less efficient for metals with low electron densities.

The enhancement factor of momentum distribution of annihilating electron‐positron pairs ε MD (p), at metal surface is investigated, for the first time in the literature.

This parameter at the clean Al surface appears to be a decreasing function of momentum, in spite of its behavior in the bulk : Anna Rubaszek.Step I: Write down a classical Lagrangian density in terms of the field.

This is the creative part because there are lots of possible Lagrangians. After this step, everything else is automatic. Step II: Calculate the momentum density and work out the Hamiltonian density in terms of fields. Step III: Now treat the fields and momentum density as.