Spectral properties and new interpolating solution of Anderson model

A new approach to many-body quasiparticle dynamics of the Anderson impurity model at finite temperatures is proposed in the framework of the equation-of-motion method. We find a new exact identity, which relates the one-particle and many-particle Green functions. Using this identity, it is shown that a new interpolating approximation for the one-particle Green function call be constructed. The approximation which simultaneously reproduces the weak-coupling limit and the strong coupling limit can be formulated self-consistently. This approach offers a new method for a systematic construction of the approximate interpolating dynamical solutions of strongly correlated electron models.