The cumulant expansion approach for strongly correlated electron models
作者:
R. Citro,
M. Marinaro,
期刊:
AIP Conference Proceedings
(AIP Available online 1903)
卷期:
Volume 695,
issue 1
页码: 268-280
ISSN:0094-243X
年代: 1903
DOI:10.1063/1.1639595
出版商: AIP
数据来源: AIP
摘要:
In a large variety of systems, like the high‐temperature superconductors, the dominant parameter of the system is the on‐site Coulomb repulsion that becomes comparable with the kinetic energy in the vicinity of the metal‐insulator transition. This implies that perturbation expansions must include this interaction in the zeroth order Hamiltonian and treat the hopping term as a perturbation. Thus, one gets a situation radically different from the usual one in which the particles are initially free and needs to develop a nonstandard perturbation theory based on a cumulant expansion. In this paper, we revisit the general formalism of the cumulant expansion approach for the single band and two‐band Hubbard model, being interested in introducing a systematic way to perform approximations which take into account cooperative phenomena. As an example we analyze the effect of the charge fluctuations on the single‐particle spectral properties. © 2003 American Institute of Physics
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