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arXiv · 1806.05639

The Generalized Kadanoff-Baym Ansatz with Initial Correlations

Daniel Karlsson·Robert van Leeuwen·Enrico Perfetto·Gianluca Stefanucci
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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.

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Daniel Karlsson, Robert van Leeuwen, Enrico Perfetto, Gianluca Stefanucci. 2018-06-14. The Generalized Kadanoff-Baym Ansatz with Initial Correlations. https://doi.org/10.1103/physrevb.98.115148

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