Rigorous derivation of the meanfield Green functions of the twoband Hubbard model of superconductivity
Abstract
The Green function (GF) equation of motion technique for solving the effective twoband Hubbard model of highT_{c} superconductivity in cuprates (Plakida et al 1995 Phys. Rev. B 51 16599, Plakida et al 2003 JETP 97 331) rests on the Hubbard operator (HO) algebra. We show that, if we take into account the invariance to translations and spin reversal, the HO algebra results in invariance properties of several specific correlation functions. The use of these properties allows rigorous derivation and simplification of the expressions of the frequency matrix (FM) and of the generalized meanfield approximation (GMFA) Green functions (GFs) of the model. For the normal singlethopping and anomalous exchange pairing correlation functions which enter the FM and GMFAGFs, an approximation procedure based on the identification and elimination of exponentially small quantities is described. It secures the reduction of the correlation order to GMFAGF expressions.
 Publication:

Journal of Physics A Mathematical General
 Pub Date:
 September 2007
 DOI:
 10.1088/17518113/40/37/001
 arXiv:
 arXiv:0704.0692
 Bibcode:
 2007JPhA...4011205A
 Keywords:

 Condensed Matter  Superconductivity;
 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 16 pages, Submitted to J. Phys. A: Mathematical and Theoretical