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Full-Text Articles in Physical Sciences and Mathematics
Optical Theorem And Multiple-Scattering Theory: Electronic States In Disordered Transion-Metals, L. Schwartz, A. Bansil
Optical Theorem And Multiple-Scattering Theory: Electronic States In Disordered Transion-Metals, L. Schwartz, A. Bansil
Arun Bansil
In disordered systems, apparently reasonable decoupling procedures can lead to negative densities of electronic states near resonant d bands. By applying the optical theorem to the multiple-scattering series we can determine a prior whether a given decoupling will necessarily yield positive results. Since none of the extensions of the coherent-potential approximation to amorphous systems is found to meet this requirement, we propose a new scheme which is both self-consistent and guaranteed to give a positive spectrum.
Optical Theorem And Multiple-Scattering Theory: Electronic States In Substitutional Alloys, L. Schwartz, A. Bansil
Optical Theorem And Multiple-Scattering Theory: Electronic States In Substitutional Alloys, L. Schwartz, A. Bansil
Arun Bansil
When multiple-scattering theory is used to describe the electronic properties of disordered transition-metal systems, decoupling procedures which appear to be physically reasonable can lead to negative densities of states in the vicinity of the resonant d bands. We present a method, based on the application of the optical theorem to the total scattering operator, that allows us to determine a priori which approximation schemes can be relied upon to produce a positive spectrum. The application of this method to substitutionally disordered binary alloys is discussed here. We find that both the average-t-matrix and coherent-potential approximations will always yield nonnegative densities …
Further Analysis Of Electronic States In The Muffin-Tin Model Of A Disordered Alloy, L. Schwartz, A. Bansil
Further Analysis Of Electronic States In The Muffin-Tin Model Of A Disordered Alloy, L. Schwartz, A. Bansil
Arun Bansil
Several new results on the evaluation of the spectral function A(k⃗,E) and average density of states ρ(E) in a realistic model of a substitutional binary alloy are presented. This work is primarily concerned with the conditions under which a given approach can be relied upon to yield a non-negative spectrum. In the average t matrix and coherent-potential approximations, a link is established between the sign of A(k⃗,E) and the Argand diagram for the energy-shell matrix elements τL of the effective atomic scattering operators: If τL lies within the unitarity circle, then A(k⃗,E)>0. The connection between this result and our …