The Generalized Kadanoff-Baym Ansatz with Initial Correlations
Abstract
Within the non-equilibrium Green's function (NEGF) formalism, the Generalized Kadanoff-Baym Ansatz (GKBA) has stood out as a computationally cheap method to investigate the dynamics of interacting quantum systems driven out of equilibrium. Current implementations of the NEGF--GKBA, however, suffer from a drawback: real-time simulations require {\em noncorrelated} states as initial states. Consequently, initial correlations must be built up through an adiabatic switching of the interaction before turning on any external field, a procedure that can be numerically highly expensive. In this work, we extend the NEGF--GKBA to allow for {\em correlated} states as initial states. Our scheme makes it possible to efficiently separate the calculation of the initial state from the real-time simulation, thus paving the way for enlarging the class of systems and external drivings accessible by the already successful NEGF--GKBA. We demonstrate the accuracy of the method and its improved performance in a model donor-acceptor dyad driven out of equilibrium by an external laser pulse.
Cite
@article{arxiv.1806.05639,
title = {The Generalized Kadanoff-Baym Ansatz with Initial Correlations},
author = {Daniel Karlsson and Robert van Leeuwen and Enrico Perfetto and Gianluca Stefanucci},
journal= {arXiv preprint arXiv:1806.05639},
year = {2018}
}