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The time evolution in quantum many-body systems after external excitations is attracting high interest in many fields. The theoretical modeling of these processes is challenging, and the only rigorous quantum-dynamics approach that can…

Strongly Correlated Electrons · Physics 2020-07-01 J. -P. Joost , N. Schlünzen , M. Bonitz

Real-time nonequilibrium Green functions (NEGF) have been very successful to simulate the dynamics of correlated many-particle systems far from equilibrium. However, NEGF simulations are computationally expensive since the effort scales…

Strongly Correlated Electrons · Physics 2023-12-27 Karsten Balzer , Niclas Schlünzen , Hannes Ohldag , Jan-Philip Joost , Michael Bonitz

The dynamics of strongly correlated fermions following an external excitation reveals extremely rich collective quantum effects. Examples are fermionic atoms in optical lattices, electrons in correlated materials, and dense quantum plasmas.…

Strongly Correlated Electrons · Physics 2020-02-26 Niclas Schluenzen , Jan-Philip Joost , Michael Bonitz

This article presents an overview on recent progress in the theory of nonequilibrium Green functions (NEGF). NEGF, presently, are the only \textit{ab-initio} quantum approach that is able to study the dynamics of correlations for long times…

Strongly Correlated Electrons · Physics 2019-12-20 N. Schluenzen , S. Hermanns , M. Scharnke , M. Bonitz

The Hubbard model is a prototype for strongly correlated many-particle systems, including electrons in condensed matter and molecules, as well as for fermions or bosons in optical lattices. While the equilibrium properties of these systems…

Strongly Correlated Electrons · Physics 2014-09-10 Sebastian Hermanns , Niclas Schlünzen , Michael Bonitz

Simulations of interacting electrons and bosons out of equilibrium, starting from first principles and aiming at realistic multiscale scenarios, is a grand theoretical challenge. Here, using the formalism of nonequilibrium Green's functions…

Strongly Correlated Electrons · Physics 2022-04-06 Yaroslav Pavlyukh , Enrico Perfetto , Daniel Karlsson , Robert van Leeuwen , Gianluca Stefanucci

The ultrafast hole dynamics triggered by the photoexcitation of molecular targets is a highly correlated process even for those systems, like organic molecules, having a weakly correlated ground state. We here provide a unifying framework…

Chemical Physics · Physics 2021-07-21 Yaroslav Pavlyukh , Enrico Perfetto , Gianluca Stefanucci

The Non-equilibrium Green's function (NEGF) formalism is a particularly powerful method to simulate the quantum transport properties of nanoscale devices such as transistors, photo-diodes, or memory cells, in the ballistic limit of…

The nonequilibrium dynamics of strongly-correlated fermions in lattice systems have attracted considerable interest in the condensed matter and ultracold atomic-gas communities. While experiments have made remarkable progress in recent…

Strongly Correlated Electrons · Physics 2017-05-03 N. Schluenzen , J. -P. Joost , F. Heidrich-Meisner , M. Bonitz

We introduce diagrammatic technique for Hubbard nonequilibrium Green functions (NEGF). The formulation is an extension of equilibrium considerations for strongly correlated lattice models to description of current carrying molecular…

Mesoscale and Nanoscale Physics · Physics 2016-11-04 Feng Chen , Maicol A. Ochoa , Michael Galperin

We have recently proposed a Nonequilibrium Green's Function (NEGF) approach to include Auger decay processes in the ultrafast charge dynamics of photoionized molecules. Within the so called Generalized Kadanoff-Baym Ansatz the fundamental…

Other Condensed Matter · Physics 2018-10-17 F. Covito , E. Perfetto , A. Rubio , G. Stefanucci

We employ Non-equilibrium Green's functions (NEGF) to describe the real-time dynamics of an adsorbate-surface model system exposed to ultrafast laser pulses. For a finite number of electronic orbitals, the system is solved exactly and…

Mesoscale and Nanoscale Physics · Physics 2016-05-04 E. Boström , M. Hopjan , A. Kartsev , C. Verdozzi , C. -O. Almbladh

The extraordinary quantum properties of nonequilibrium systems governed by dissipative dynamics have become a focal point in contemporary scientific inquiry. The Nonequilibrium Green's Functions (NEGF) theory provides a versatile method for…

Materials Science · Physics 2024-02-19 Gianluca Stefanucci

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.…

Strongly Correlated Electrons · Physics 2018-10-03 Daniel Karlsson , Robert van Leeuwen , Enrico Perfetto , Gianluca Stefanucci

We present an efficient implemention of a non-equilibrium Green function (NEGF) method for self-consistent calculations of electron transport and forces in nanostructured materials. The electronic structure is described at the level of…

Mesoscale and Nanoscale Physics · Physics 2015-06-04 Jingzhe Chen , Kristian S. Thygesen , Karsten W. Jacobsen

We have developed a time propagation scheme for the Kadanoff-Baym equations for general inhomogeneous systems. These equations describe the time evolution of the nonequilibrium Green function for interacting many-body systems in the…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Adrian Stan , Nils Erik Dahlen , Robert van Leeuwen

Nonequilibrium Green's functions provide a powerful framework for studying quantum many-body dynamics including the laser-induced dynamics in solids. The Non-Equilibrium Systems Simulation package (NESSi) offers an efficient platform for…

The nonequilibrium Green's function formalism provides a versatile and powerful framework for numerical studies of nonequilibrium phenomena in correlated many-body systems. For calculations starting from an equilibrium initial state, a…

Strongly Correlated Electrons · Physics 2024-07-11 Matthias Murray , Hiroshi Shinaoka , Philipp Werner

The numerical solution of the Kadanoff-Baym nonlinear integro-differential equations, which yields the non-equilibrium Green's functions (NEGFs) of quantum many-body systems, poses significant computational challenges due to its high…

Distributed, Parallel, and Cluster Computing · Computer Science 2025-05-27 Jia Yin , Khaled Z. Ibrahim , Mauro Del Ben , Jack Deslippe , Yang-hao Chan , Chao Yang

The non-equilibrium Green's function (NEGF) approach offers a practical framework for simulating various phenomena in mesoscopic systems. As the dimension of electronic devices shrinks to just a few nanometers, the need for new…

Mesoscale and Nanoscale Physics · Physics 2025-04-09 Vahid Mosallanejad , Kuei-Lin Chiu , Wenjie Dou
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