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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Збережено в:
Бібліографічні деталі
Дата:1998
Автори: Izyumov, Yu.A., Chashchin, N.I.
Формат: Стаття
Мова:English
Опубліковано: Інститут фізики конденсованих систем НАН України 1998
Назва видання:Condensed Matter Physics
Онлайн доступ:http://dspace.nbuv.gov.ua/handle/123456789/118631
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Назва журналу:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Цитувати: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
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Резюме: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.