Dynamic Hubbard model: Effect of finite boson frequency

[摘要] Dynamic Hubbard models describe coupling of a boson degree of freedom to the on-site electronic double occupancy. In the limit of infinite boson frequency this coupling gives rise to a correlated hopping term in the effective Hamiltonian and to superconductivity when the Fermi level is near the top of the band. Here we study the effect of finite boson frequency through a generalized Lang-Firsov transformation and a high-frequency expansion. It is found that finite frequency enhances the tendency to superconductivity in this model.

[发布日期] 2003-12-01

[关键词] SUPERCONDUCTIVITY