Properties of the Bound States on a Hexagonal Lattice

M. Bak Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland

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Two electrons on a lattice pose an interesting problem which can be solved exactly. When the effective interactions are strong enough, the bound states are formed. The properties of such bound pairs in an extended Hubbard model are examined for both signs of nearest neighbor hopping integral t. The stabilization of s*-wave pairing is found for t < 0 and of f-wave for t > 0. Phase diagrams for the existence of none, one or two s*-wave solutions are calculated.

DOI: 10.12693/APhysPolA.111.781 PACS numbers: 71.10.Fd, 74.20.Rp, 71.27.+a, 71.10.Hf