ATTRACTIVE HUBBARD PAIRING IN A TRIANGULAR LATTICE

By taking advantage of a mapping method which allows an exact solution of the few-electron case within the extended Hubbard Hamiltonian, the electron pairing and the hole pairing in a triangular lattice are ana lyzed by looking at the binding energy and the coherence length. The m ethod consists on mapping the original many-body problem onto an equiv alent tight-binding one with impurities in a higher dimensional space, where the impurity symmetry is considered so as to make the analysis on a truly large system. A clear pairing asymmetry between the bonding states and the anti-bonding states is observed; the latter is stronge r. In addition, the results of the binding energy between holes show a n asymptotic transition into the behavior of one-dimensional systems i n the strong-interaction region.