Physical Review B
Comparison of the electronic structure of the Hubbard and t−J models within the cluster perturbation theory
V. I. Kuz’min, Sergey V. Nikolaev, Sergei G. Ovchinnikov
Abstract
Electronic dispersion and density of states (DOS) have been calculated for the Hubbard model and the $t\ensuremath{-}J$ and $t\ensuremath{-}{J}^{*}$ models with three-site correlated hopping by the cluster perturbation theory. We have found a rather strong quantitative difference both in dispersion and DOS at all doping for the Hubbard and $t\ensuremath{-}J$ models at the energy scale $\ensuremath{\omega}\ensuremath{\gtrsim}t$. The three-site correlated hopping addition results in an almost negligible difference for the Hubbard and $t\ensuremath{-}{J}^{*}$ models. Close to the Fermi energy, at the scale $\ensuremath{\omega}\ensuremath{\lesssim}J$, the electronic structure of all three models is similar. We have found the line of zeros of the Green function for the $t\ensuremath{-}J$ model that has been previously obtained for the Hubbard model by cellular dynamical mean-field theory calculations.