tJ -model in terms of equations with variational derivatives
For a tJ -model in the X -operators representation a generating functional of the field describing fluctuations of matrix elements of electron hopping on a lattice is presented. The first order functional derivative with respect to this field determines the electron Green function, while the seco...
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| Date: | 1998 |
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| Main Authors: | , |
| Format: | Article |
| Language: | English |
| Published: |
Інститут фізики конденсованих систем НАН України
1998
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| Series: | Condensed Matter Physics |
| Online Access: | http://dspace.nbuv.gov.ua/handle/123456789/118631 |
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| Journal Title: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Cite this: | tJ -model in terms of equations with variational derivatives / Yu.A. Izyumov, N.I. Chashchin // Condensed Matter Physics. — 1998. — Т. 1, № 1(13). — С. 41-56. — Бібліогр.: 7 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| Summary: | For a tJ -model in the X -operators representation a generating functional
of the field describing fluctuations of matrix elements of electron hopping
on a lattice is presented. The first order functional derivative with respect
to this field determines the electron Green function, while the second order
derivatives determine the boson Green functions of collective excitations
in the system. Thus, the Kadanoff-Baym approach in the theory of fermi
system with a weak Coulomb interaction is generalized on the opposite
limit of systems with strong correlations. A chain of equations for different
order variational derivatives were obtained, and a method was suggested
based on iterations over the parameters of a tJ -model: the hopping matrix
element and the exchange integral. This approach corresponds to a
self-consistent Born approximation, not for the effective but for the original
Hamiltonian. A scheme of calculation of the dynamical spin susceptibility
is analyzed with self-consistent corrections of the first and second order.
Connection of this approach with the diagram technique for X -operators
is discussed. |
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