Repulsive bound-electron pairs in a Peierls lattice

A new class of repulsive bound-electron pairs have been found in a Peierls lattice within the Hubbard model for energies E < 0 despite U > 0. These new repulsive bound-electron pairs have a high degree of localization as both the correlation energy U and the tS/tL hopping ratio increases. In order to study electronic correlation in Peierls lattices, our previous real space mapping method has also been extended to the so called generalized mapping method which is briefly presented here. In this paper, we concentrate our attention to discuss in detail the two-particle problem within a repulsive Hubbard model for the one-dimensional Peierls lattice.