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Non-equilibrium Green's Function (NGF) method is a powerful tool for studying the evolution of quantum many-body systems. Different types of correlations can be systematically incorporated within the formalism. The time evolution of the…

Nuclear Theory · Physics 2018-01-17 M. H. Mahzoon , P. Danielewicz , A. Rios

We put forward a practical nonequilibrium Green's function (NEGF) scheme to perform real-time evolutions of many-body interacting systems driven out of equilibrium by external fields. CHEERS is a computational tool to solve the NEGF…

Other Condensed Matter · Physics 2018-10-09 E. Perfetto , G. Stefanucci

In the nonequilibrium Green's function approach, the approximation of the correlation self-energy at the second-Born level is of particular interest, since it allows for a maximal speed-up in computational scaling when used together with…

Computational Physics · Physics 2019-11-11 Riku Tuovinen , Fabio Covito , Michael A. Sentef

The quantum dynamics of correlated fermionic or bosonic many-body systems following external excitation can be successfully studied using nonequilibrium Green functions (NEGF) or reduced density matrix methods. Approximations are introduced…

Strongly Correlated Electrons · Physics 2023-12-27 Erik Schroedter , Björn Jakob Wurst , Jan-Philip Joost , Michael Bonitz

In non-equilibrium Green's function calculations the use of the Generalized Kadanoff-Baym Ansatz (GKBA) allows for a simple approximate reconstruction of the two-time Green's function from its time-diagonal value. With this a drastic…

Strongly Correlated Electrons · Physics 2013-09-19 S. Hermanns , K. Balzer , M. Bonitz

Real-time Green's function simulations of molecular junctions (open quantum systems) are typically performed by solving the Kadanoff-Baym equations (KBE). The KBE, however, impose a serious limitation on the maximum propagation time due to…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 S. Latini , E. Perfetto , A. -M. Uimonen , R. van Leeuwen , G. Stefanucci

The quantum dynamics of fermionic or bosonic many-body systems following external excitation can be successfully studied using two-time nonequilibrium Green's functions (NEGF) or single-time reduced density matrix methods. Approximations…

Strongly Correlated Electrons · Physics 2022-07-12 Erik Schroedter , Jan-Philip Joost , Michael Bonitz

Through the Non-Equilibrium Green's Function (NEGF) formalism, quantum-scale device simulation can be performed with the inclusion of electron-phonon scattering. However, the simulation of realistically sized devices under the NEGF…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 Stephen Cauley , Mathieu Luisier , Venkataramanan Balakrishnan , Gerhard Klimeck , Cheng-Kok Koh

An efficient implementation of the nonequilibrium Green function (NEGF) method combined with the density functional theory (DFT) using localized pseudo-atomic orbitals (PAOs) is presented for electronic transport calculations of a system…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Taisuke Ozaki , Kengo Nishio , Hiori Kino

This review deals with the nonequilibrium Green's function (NEGF) method applied to the problems of energy transport due to atomic vibrations (phonons), primarily for small junction systems. We present a pedagogical introduction to the…

Mesoscale and Nanoscale Physics · Physics 2013-05-28 Jian-Sheng Wang , Bijay Kumar Agarwalla , Huanan Li , Juzar Thingna

The nonequilibrium dynamics of correlated many-particle systems is of interest in connection with pump-probe experiments on molecular systems and solids, as well as theoretical investigations of transport properties and relaxation…

Computational Engineering, Finance, and Science · Computer Science 2020-08-26 Michael Schüler , Denis Golež , Yuta Murakami , Nikolaj Bittner , Andreas Hermann , Hugo U. R. Strand , Philipp Werner , Martin Eckstein

One of the challenges in diagrammatic simulations of nonequilibrium phenomena in lattice models is the large memory demand for storing momentum-dependent two-time correlation functions. This problem can be overcome with the recently…

Strongly Correlated Electrons · Physics 2025-10-23 Maksymilian Środa , Ken Inayoshi , Hiroshi Shinaoka , Philipp Werner

Theory of non-equilibrium Green's function (NGF) provides a practical framework for studying quantum many-body systems out of equilibrium. Extending the previous mean field approach developed for nuclear systems in one dimension with NGF,…

Nuclear Theory · Physics 2020-08-26 Hao Lin , Hossein Mahzoon , Arnau Rios , Pawel Danielewicz

A nonequilibrium Green's functions (NEGF) approach for spatially inhomogeneous, strongly correlated artificial atoms is presented and applied to compute the time-dependent properties while starting from a (correlated) initial few-electron…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 K Balzer , M Bonitz

Correlated classical and quantum many-particle systems out of equilibrium are of high interest in many fields, including dense plasmas, correlated solids, and ultracold atoms. Accurate theoretical description of these systems is challenging…

Statistical Mechanics · Physics 2026-04-02 Erik Schroedter , Michael Bonitz

This work describes a novel simulation approach that combines machine learning and device modelling simulations. The device simulations are based on the quantum mechanical non-equilibrium Greens function (NEGF) approach and the machine…

Computational Engineering, Finance, and Science · Computer Science 2023-09-19 Preslav Aleksandrov , Ali Rezaei , Nikolas Xeni , Tapas Dutta , Asen Asenov , Vihar Georgiev

The theory of Self-Consistent Green's Function (SCGF) is reformulated in an explicit Nambu-covariant fashion for applications to many-body systems at non-zero temperature in symmetry-broken phases. This is achieved by extending the…

Nuclear Theory · Physics 2025-07-09 M. Drissi , A. Rios , C. Barbieri

Computational difficulties aside, nonequilibrium Green's functions appear ideally suited for investigating the dynamics of central nuclear reactions. Many particles actively participate in those reactions. At the two energy extremes for the…

Nuclear Theory · Physics 2018-05-17 Hossein Mahzoon , Pawel Danielewicz , Arnau Rios

The nonequilibrium Green's functions (NEGF) approach is a versatile theoretical tool, which allows to describe the electronic structure, spectroscopy and dynamics of strongly correlated systems. The applicability of this method is, however,…

Strongly Correlated Electrons · Physics 2018-06-27 Michael Schüler , Martin Eckstein , Philipp Werner

Non equilibrium Green's function methods are regularly used to calculate current and charge densities in nanoscale (both molecular and semiconductor) conductors under bias. This method is mainly used for ballistic conduction but may be…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 M. Paulsson