Resonant Two-Electron Pairs in a Simple Cubic Lattice

The properties of resonant two-electron pairs are examined in three-dimensional simple cubic extended Hubbard tUW model, in s- and d- symmetry channels, in the limit of empty lattice. Lattice Green function technique is applied to calculate the scattering amplitude by means of matrix for any energy in the band on ΓR line within the Brillouin zone. The analysis shows the persistence of resonant states even for Coulomb interactions so weak that the equation for the resonant states is not formally fulfilled. The difference in behavior of resonances controlled by on-site and intersite Coulomb interactions is found. The ranges of applicability of approximate formula for the actual position of resonant peak and its width are shown.