Modern Band Theory of Disordered Alloys: Basic Concepts Including a Discussion of Momentum Densities

Abstract

An overview of some of the basic concepts in the modern first-principles band theory of disordered alloys is given. The question of how the notion of Bloch energy bands and Fermi surfaces generalizes to the case of the disordered system, insofar as the average electronic spectrum is concerned, is stressed. The theory is illustrated with examples chosen from the work on binary alloys; a few examples of the very recent studies of disordered phases of the high-T c superconductors are also included. The application of the alloy theory to obtain electron and electron-positron momentum densities involved in the analysis of Compton scattering and positron annihilation (angular correlation) experiments in alloys is discussed, with a selection of relevant theoretical and experimental studies.

Renormalization offlevels away from the Fermi energy in electron excitation spectroscopies: Density-functional results for Nd2−xCeJarlborg1, Barbiellini2, Lin3 et al. 2011Phys. Rev. BSelf Cite

“…A RE ferromagnetic metallic solution is very close in energy, and it is more convenient to use for calculating excitation energies. Accordingly, we will study excitations from the fictitious ferromagnetic ground state for x = 0, which are very similar to the excitations of the metallic compound with x = 0 [30][31][32]. Our basis set includes ℓ ≤ 3 for Nd, ℓ ≤ 2 for Cu and O, and ℓ ≤ 1 for empty spheres, two of which are inserted per formula unit in the most open part of the structure.…”

Electrical and magnetic properties of thin films of the spin-filter material CrVTiAl

“…The effects of substitutional disorder were investigated via ab initio calculations carried out using the all electron, fully charge-and spin-selfconsistent Korringa-Kohn-Rostocker coherent-potentialapproximation (KKR-CPA) scheme. [33][34][35][36][37] The KKR-CPA approximates the average properties of the disordered system by averaging these properties over a site embedded in a self-consistently determined effective medium. The KKR-CPA goes beyond the simpler virtual crystal approximation (VCA) and average t-matrix approximation (ATA) 38 .…”

X-ray absorption near-edge spectra of overdopedLa2−xSrxCuO4high-Ahmed1, Das2, Kas3 et al. 2011Phys. Rev. BSelf Cite142140View full textAdd to dashboardCite

“…In our QP-GW approach, we start with a tight-binding single band bare dispersion ξ k where the parameters are obtained by fitting to the first-principles LDA dispersion. [23][24][25] The values of the tight-binding parameters used in LSCO are from Ref. 1.…”