Superfluid density and the drude weight of the hubbard model

We study the superfluid density and the Drude weight of the Hubbard model by investigating two different limiting behaviors of the current-current correlation function. These quantities provide criteria which allow one to distinguish between superconducting, metallic, and insulating ground states of an interacting many-body system. Monte Carlo calculations are performed to study these quantities. © 1992 The American Physical Society.