Short-time character of corrections to the generalized Kadanoff-Baym Ansatz

Abstract

An approximation of the Green function based on the Generalized Kadanoff-Baym Ansatz and its correction is tested on the electron tunneling through a single atom, incorporating the on-site second-order Born interaction. Time evolution resulting from the corresponding kinetic equation for the density matrix is compared with the direct solution of the non-equilibrium Green functions. It is demonstrated that the short-time nature of corrections beyond the Generalized Kadanoff-Baym Ansatz enables their effective numerical approximation.