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The Kadanoff-Baym (KB) equations are solved numerically for infinite nuclear matter. In particular we calculate correlation energies and correlation times. Approximating the Green's functions in the KB collision kernel by the free Green's…

Nuclear Theory · Physics 2009-11-07 H. S. Köhler , K. Morawetz

We present quantum electron transport theory that incorporates dynamical effects of motion of atoms on electrode-molecule interfaces in the calculations of the electric current. The theory is based on non-equilibrium Green's functions. We…

Mesoscale and Nanoscale Physics · Physics 2018-08-14 Vincent F. Kershaw , Daniel S. Kosov

For a minimal Hubbard-type system at different interaction strengths U, we investigate the density-response for an excitation beyond the linear regime using the generalized Kadanoff-Baym ansatz (GKBA) and the second Born (2B) approximation.…

Strongly Correlated Electrons · Physics 2015-06-12 K. Balzer , S. Hermanns , M. Bonitz

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

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

A nonequilibrium Green's functions approach to the collective response of correlated Coulomb systems at finite temperature is presented. It is shown that solving Kadanoff-Baym type equations of motion for the two-time correlation functions…

Strongly Correlated Electrons · Physics 2009-02-11 N. -H. Kwong , M. Bonitz

On the basis of the Kadanoff-Baym (KB) varient of the time dependent Green's function method a new ansatz for the approximation of a spectral function is offered. The ansatz possesses all the advantages of quasiparticle (QP) and extended…

Statistical Mechanics · Physics 2009-11-13 M. Arshad , A. S. Kondratyev , Imran Siddique

A fast time propagation method for nonequilibrium Green's functions based on the generalized Kadanoff--Baym Ansatz (GKBA) is applied to a lattice system with a symmetry-broken equilibrium phase, namely an excitonic insulator. The adiabatic…

Strongly Correlated Electrons · Physics 2018-12-05 Riku Tuovinen , Denis Golež , Michael Schüler , Philipp Werner , Martin Eckstein , Michael A. Sentef

We present a quantum kinetic approach for the time-resolved description of many-body effects in photoionization processes in atoms. The method is based on the non-equilibrium Green functions formalism and solves the Keldysh/Kadanoff-Baym…

Atomic Physics · Physics 2015-05-13 D. Hochstuhl , K. Balzer , S. Bauch , M. Bonitz

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

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

We present a theory of molecular motors based on the Ehrenfest dynamics for the nuclear coordinates and the adiabatic limit of the Kadanoff-Baym equations for the current-induced forces. Electron-electron interactions can be systematically…

Mesoscale and Nanoscale Physics · Physics 2018-07-25 Miroslav Hopjan , Gianluca Stefanucci , Enrico Perfetto , Claudio Verdozzi

Understanding the dynamics of nonequilibrium quantum many-body systems is an important research topic in a wide range of fields across condensed matter physics, quantum optics, and high-energy physics. However, numerical studies of…

Strongly Correlated Electrons · Physics 2024-12-11 Yuanran Zhu , Jia Yin , Cian C. Reeves , Chao Yang , Vojtech Vlcek

A recently developed method for incorporating initial binary correlations into the Kadanoff-Baym equations (KBE) is used to derive a generalized T-matrix approximation for the self-energies. It is shown that the T-matrix obtains additional…

Statistical Mechanics · Physics 2015-06-25 D. Semkat , D. Kremp , M. Bonitz

The interaction of electrons with quantized phonons and photons underlies the ultrafast dynamics of systems ranging from molecules to solids, giving rise to a plethora of physical phenomena experimentally accessible using time-resolved…

Strongly Correlated Electrons · Physics 2023-12-04 Y. Pavlyukh , R. Tuovinen , E. Perfetto , G. Stefanucci

The HF-GKBA offers an approximate numerical procedure for propagating the two-time non-equilibrium Green's function(NEGF). Here we compare the HF-GKBA to exact results for a variety of systems with long and short-range interactions,…

Computational Physics · Physics 2023-02-15 Cian C. Reeves , Jia Yin , Yuanran Zhu , Khaled Z. Ibrahim , Chao Yang , Vojtech Vlcek

The interaction with time-dependent external fields, especially the interplay between time-dependent driving and quantum correlations, changes the familiar picture of electron transport through nanoscale systems. Although the exact solution…

Mesoscale and Nanoscale Physics · Physics 2020-02-13 Thomas D. Honeychurch , Daniel S. Kosov

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

Non-equilibrium Green's function theory for non-adiabatic effects in quantum transport [Kershaw and Kosov, J.Chem. Phys. 2017, 147, 224109 and J. Chem. Phys. 2018, 149, 044121] is extended to the case of interacting electrons. We consider a…

Mesoscale and Nanoscale Physics · Physics 2019-02-20 Vincent F. Kershaw , Daniel S. Kosov

A method for deriving quantum kinetic equations with initial correlations is developed on the basis of the nonequilibrium Green's function formalism. The method is applicable to a wide range of correlated initial states described by…

Statistical Mechanics · Physics 2009-10-31 V. G. Morozov , G. Röpke