抄録
We study the effects of electron correlation on transport through an interacting region connected to multi-mode leads based on the perturbation expansion with respect to the inter-electron interaction. At zero temperature the conductance defined in the Kubo formalism can be written in terms of a single-particle Green's function at the Fermi energy, and it can be mapped onto a transmission coefficient of the free quasiparticles described by an effective Hamiltonian. We apply this formulation to a two-dimensional Hubbard model of finite size connected to two noninteracting leads. We calculate the conductance in the electron-hole symmetric case using the order U2 self-energy. The conductance shows several maximums in the U dependence in some parameter regions of ty/tx, where tx (ty) is the hopping matrix element in the x- (y-) directions. This is caused by the resonance occurring in some of the subbands, and is related with the U dependence of the eigenvalues of the effective Hamiltonian.
