Perturbed Charge Density Research Articles

Charge density perturbation around impurities in metals

physica status solidi (b)Volume 85, Issue 2 p. K85-K88 Short Note Charge density perturbation around impurities in metals E. Mrosan, E. Mrosan Sektion Physik der Technischen Universität Dresden, Wissenschaftsbereich Theoretische PhysikSearch for more papers by this authorG. LEHMANN, G. LEHMANN Zentralinstitut fur Festkorperphysik und Werkstofforschung der Akademie d e r Wissenschaften d e r DDR, DresdenSearch for more papers by this author E. Mrosan, E. Mrosan Sektion Physik der Technischen Universität Dresden, Wissenschaftsbereich Theoretische PhysikSearch for more papers by this authorG. LEHMANN, G. LEHMANN Zentralinstitut fur Festkorperphysik und Werkstofforschung der Akademie d e r Wissenschaften d e r DDR, DresdenSearch for more papers by this author First published: 1 February 1978 https://doi.org/10.1002/pssb.2220850250Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume85, Issue21 February 1978Pages K85-K88 RelatedInformation

Au197isomer-shift studies of charge-density perturbations in Au-based alloys

M\"ossbauer spectra for $^{197}\mathrm{Au}$ have been obtained for nominally 1-, 2-, and 4-at.% solid solutions of the elements Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Ag, Cd, In, Sn, and Sb with high-purity gold at 4.2\ifmmode^\circ\else\textdegree\fi{}K. The change in isomer shift from that of pure $^{197}\mathrm{Au}$ arising from the charge-density perturbation by the impurity have been extrapolated to 0-at.% solute for these elements to determine the influence of impurities in gold upon the electronic conduction band. The resultant isomer shifts (corrected for volume effects) are presented in comparison to the residual electrical resistivity of the same impurities in gold and provide a new and more rigid constraint upon the character of the scattering potential at an impurity site in gold.

Low frequency stability theory of axisymmetric toroidal plasma. I. General theory

A formalism for discussing low frequency electrostatic modes in a general axisymmetric toroidal geometry is developed. Particular emphasis is laid on the conflict between the requirements of long parallel wavelengths and double toroidal periodicity in the presence of shear. Expressions for the perturbed charge density useful for examining flute, drift and trapped particle modes are presented.

Asymptotic and Pre‐Asymptotic Region of Charge Density Oscillation around Impurities in Dilute Copper‐Based Alloys

AbstractComparison of the wipe‐out numbers for the first and second order quadrupole effects in the magnetic resonance of matrix nuclei shows that Friedel's asymptotic charge density perturbation formula is not valid for the near‐region around the impurity. On the basis of Alfred's and Van Ostenburg's pre‐asymptotic theory, wipe‐out numbers characteristic of the second order quadrupole effect are calculated for Cu‐Zn, Cu‐Ga, and Cu‐Ge dilute alloys and good agreement with the experimental results is found. I n spite of this success this theory is unable to describe adequately, the field gradients measured a t the first and second coordination shells near the impurity.

Nonlinear Dynamics of a Single Harmonic Loss-Cone Flute Mode

The nonlinear evolution of a single-wavelength, longitudinal flute mode with frequency near a harmonic of the cyclotron frequency is determined. It is shown that only a small-amplitude wave is needed to destroy the linearly coherent contributions of different gyrating particles to the perturbed charge density. This nonlinear smearing of the cyclotron resonance is accomplished by vortex filament motion of the hot particles in phase space, and leads to rapid stabilization and subsequent damping of the linearly unstable resonant modes that occur in hot-cold multicomponent loss-cone systems. In such a system with a typical hot-particle Larmor radius R, a mode with wave vector k gains energy from the low-velocity, inverted population hot particles until an energy is attained of the order (kR)−2 times the hot-particle kinetic energy. This field energy then decays, being absorbed by the high-velocity, normally populated hot particles.

Electron-Phonon Interaction and Phonon Dispersion Relations Using the Augmented-Plane-Wave Method

A new version of the "Schr\"odinger method" for treating the electron-phonon matrix element is presented. Using the Schr\"odinger equation, the matrix element is transformed so as to obtain the first-order perturbed charge density of the valence electrons self-consistently as the sum of two parts. The first or "bound" part corresponds to the rigid movement of the valence charge density inside a volume ${V}_{0}$ (chosen for maximum convenience) in the unit cell with the ion core, while the second or "deformation" part represents the rest of the perturbation and may be calculated as the self-consistent response to a weak effective driving potential, called the residual potential, which does not contain the deep well near the core. The screened matrix element is obtained, and the relationship to Bardeen's method and to the more recent pseudopotential methods is discussed. A certain resemblance of the residual potential to the Heine-Abarenkov model potential is pointed out. Finally, the dynamical matrix is transformed without approximation to be written as the sum of an interaction between pseudoatoms and a deformation part. The advantages of such a recasting are discussed. Explicit expressions are derived based on the APW representation of the valence wave functions, since it is intended to apply the formalism to transition metals and other more complicated solids.