Dynamical Mean-Field Theory on the Basis of the Fourth-Order Perturbation Expansion

Adopting a fourth-order perturbation expansion as a solver for the impurity problem, we develop a dynamical mean-field theory for the Hubbard model. Zero temperature Mott transition is discussed by calculating a quasiparticle weight z in the infinite dimensional Hubbard model at half filling. We obtain fairly good agreement with the result on the basis of the numerical renormalization group as an impurity solver, revising the result based on the second-order perturbation expansion as the impurity solver.