Tight-binding coherent-potential approximation including off-diagonal disorder

1989 ◽  
Vol 40 (18) ◽  
pp. 12196-12200 ◽  
Author(s):  
D. A. Papaconstantopoulos ◽  
A. Gonis ◽  
P. M. Laufer
Keyword(s):  
Tight Binding ◽  
Coherent Potential Approximation ◽  
Potential Approximation ◽  
Diagonal Disorder

AN AUGMENTED SPACE-BASED CLUSTER COHERENT POTENTIAL APPROXIMATION: APPLICATION TO CuAu AND NiAl ALLOYS

2011 ◽  
Vol 25 (05) ◽  
pp. 735-745
Author(s):  
MOSHIOUR RAHAMAN ◽  
ABHIJIT MOOKERJEE
Keyword(s):  
Magnetic Properties ◽  
Tight Binding ◽  
Local Environment ◽  
Coherent Potential Approximation ◽  
Orbital Method ◽  
Potential Approximation ◽  
Augmented Space ◽  
Space Formalism ◽  
Random Alloys ◽  
Linear Muffin Tin Orbital

We use cluster generalization of the coherent potential approximation in the tight-binding linear muffin-tin orbital method to account for the effect of the local environment on electronic and magnetic properties of substitutional random alloys. This theory combines the augmented space formalism and conventional tight-binding linear muffin-tin orbital methods. In particular, we shall apply the technique to the bcc-based NiAl and fcc-based CuAu alloys and also compare with other approaches.

A Tight-Binding Hamiltonian for the High-Temperature Superconductor YBa2Cu3O7

1988 ◽  
Vol 141 ◽  
Author(s):  
M.J. DeWeert ◽  
D.A. Papaconstantopoulos ◽  
W.E. Pickett
Keyword(s):  
Electronic Structure ◽  
High Temperature ◽  
Band Structure ◽  
Potential Application ◽  
Oxygen Vacancies ◽  
High Temperature Superconductor ◽  
Tight Binding ◽  
Coherent Potential Approximation ◽  
Potential Approximation

AbstractWe present a highly accurate tight-binding parametrization of the LAPW band structure of the high-temperature superconductor YBa2Cu3O7, discuss the methodology used in obtaining this fit, and its potential application to a Tight-Binding Coherent-Potential Approximation (TB-CPA) calculation of the effects of oxygen vacancies on the electronic structure.

Optical Properties of a Quantum Well of A1−x Bx Alloy Semiconductor in the Coherent Potential Approximation

2000 ◽  
Vol 639 ◽  
Author(s):  
Yuzo Shinozuka ◽  
Hirotsugu Kida ◽  
Masanori Watarikawa
Keyword(s):  
Optical Properties ◽  
Quantum Well ◽  
Tight Binding ◽  
Impurity Band ◽  
Coherent Potential Approximation ◽  
Electron Hole ◽  
Potential Approximation ◽  
Binding Model ◽  
Rectangular Array ◽  
One Dimensional

ABSTRACTWe have theoretically studied optical properties of a quantum well (QW) in which the well region is constructed from a binary alloy semiconductor A1−xBx in the coherent potential approximation (CPA). A tight binding model is used for a single particle (electron, hole, Frenkel exciton) in the well composed by a rectangular array of NxxNyxNz sites. The effect of the diagonal randomness is reduced to the coherent potential σ(E), which is assumed to be the same for all sites, and is selfconsistently determined with the average Green's function. For a slab (∞, ∞, Nz) and wire (∞, Ny, Nz), the density of states (E) is composed of Nz (or NyxNz) subbands, each shows the two (one)-dimensional van-Hove singularity. When x (or 1−x) is small, a B (A) impurity-band always appears at the lower (higher) energy side of the lowest (highest) host-band. The change of (E) and the absorption spectrum by changing the well-width and the dimensionality is discussed in detail.

scholarly journals Absorption Spectrum and Density of States of Square, Rectangular, and Triangular Frenkel Exciton Systems with Gaussian Diagonal Disorder

2017 ◽  
Vol 2017 ◽  
pp. 1-5
Author(s):  
Ibrahim Avgin ◽  
David Huber
Keyword(s):  
Density Of States ◽  
Nearest Neighbor ◽  
Elliptic Integral ◽  
Coherent Potential Approximation ◽  
Square Lattice ◽  
Integral Approach ◽  
Frenkel Exciton ◽  
Potential Approximation ◽  
Effects Of Disorder ◽  
Diagonal Disorder

Using the coherent potential approximation, we investigate the effects of disorder on the optical absorption and the density of states of Frenkel exciton systems on square, rectangular, and triangular lattices with nearest-neighbor interactions and a Gaussian distribution of transition energies. The analysis is based on an elliptic integral approach that gives results over the entire spectrum. The results for the square lattice are in good agreement with the finite-array calculations of Schreiber and Toyozawa. Our findings suggest that the coherent potential approximation can be useful in interpreting the optical properties of two-dimensional systems with dominant nearest-neighbor interactions and Gaussian diagonal disorder provided the optically active states are Frenkel excitons.

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