Accuracy of the spectral density approach for the quasiparticle excitations in the s-f model

Model spectral densities which describe the quasiparticle excitations in the s-f model are introduced and used to calculate the total quasiparticle spectrum. Their parameters are rigorously determined from the first five exactly known moments at temperature T=0. A satisfactory agreement with the exa...

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Bibliographic Details
Published in:Physica A 1987, Vol.143 (1), p.296-313
Main Authors: Nolting, Wolfgang, Oleś, Andrzej M.
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Electron states
Exact sciences and technology
Exchange interactions
Level splitting and interactions
Physics
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Summary:Model spectral densities which describe the quasiparticle excitations in the s-f model are introduced and used to calculate the total quasiparticle spectrum. Their parameters are rigorously determined from the first five exactly known moments at temperature T=0. A satisfactory agreement with the exact solution is found only for the spectral densities which take into account the damping of the scattering part of the spectrum. One of the advantages of the present method is its nonperturbative character. This makes it applicable to the systems with phase transitions as well.
ISSN:0378-4371
1873-2119
DOI:10.1016/0378-4371(87)90070-7