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Poisson Approximation to a Functional Approach for the Hubbard Model
Author(s) -
Behn U.
Publication year - 1980
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221000113
Subject(s) - hubbard model , poisson distribution , limit (mathematics) , coulomb , t j model , physics , electron , function (biology) , poisson's equation , quantum mechanics , condensed matter physics , mathematics , statistical physics , mathematical analysis , statistics , superconductivity , evolutionary biology , biology
In a previous paper the Green function for the Hubbard model is represented by a functional average of the Green function for an electron moving in a local time dependent potential Uv i ( t ) taking only the values 0 and U . Here this functional average is calculated with an ad hoc assumed Poisson distribution governing the jumps of Uv i ( t ). In a single‐site approximation the Poisson average can be calculated exactly and leads to a self‐consistent ‚dynamic’ scheme interpolating between band and atomic limit. For a half‐filled band in the paramagnetic case at zero temperature for strong Coulomb repulsion U ≈ 2 two subbands are obtained separated by a minimum of the density of states.