Regensburg 2025 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 37: Correlated Electrons: Poster

TT 37.62: Poster

Wednesday, March 19, 2025, 15:00–18:00, P4

Simulating nonequilibrium systems in the steady-state: GW+EDMFT — •Fabian Künzel — University of Hamburg, 20355 Hamburg, Germany

The Keldysh formalism for nonequilibrium Green's functions provides a versatile theoretical framework for analyzing the dynamics and structure of correlated many-body systems. To address the intrinsic cubic scaling of computational time in the Kadanoff-Baym equations (KBE) for nonequilibrium Green's functions, a truncation of the underlying memory kernel can be incorporated into the time-stepping algorithm of the NESSi simulation package. This reduces the computational cost to linear scaling with respect to the maximum simulation time. For systems where long-time dynamics extend beyond the capabilities of state-of-the-art methods, the KBE can be formulated within the Keldysh steady-state formalism. The resulting equations are then solved using a Fourier transform, enabling the description of systems with exponentially separated timescales. We aim to introduce new methods that extend the reach of the existing NESSi package and present a steady-state study of a Mott insulator, incorporating non-local correlations through a steady-state GW+EDMFT formalism.

Keywords: Nonequilibrium; Steady-state; Keldysh; GW; DMFT