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Kinetic equations governing time evolution of positions and momenta of atoms in extended systems are derived using quantum-classical ensembles within the Non-Equilibrium Statistical Operator Method (NESOM). Ions are treated classically,…

Statistical Mechanics · Physics 2009-11-13 Yu Wang , Lev Kantorovich

The Keldysh formalism for nonequilibrium Green's functions is a powerful theoretical framework for the description of the electronic structure, spectroscopy, and dynamics of strongly correlated systems. However, the underlying Kadanoff-Baym…

Strongly Correlated Electrons · Physics 2022-04-13 Christopher Stahl , Nagamalleswararao Dasari , Jiajun Li , Antonio Picano , Philipp Werner , Martin Eckstein

Since proposed in the 70s, the Non-Equilibrium Green Function (NEGF) method has been recognized as a standard approach to quantum transport simulations. Although it achieves superiority in simulation accuracy, the tremendous computational…

Mesoscale and Nanoscale Physics · Physics 2023-12-05 Yingzhanghao Zhou , Xiang Chen , Peng Zhang , Jun Wang , Lei Wang , Hong Guo

The nonequilibrium description of quantum systems requires, for more than two or three particles, the use of a reduced description to be numerically tractable. Two possible approaches are based on either reduced density matrices or…

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

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

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 Green's function method has applications in several fields in Physics, from classical differential equations to quantum many-body problems. In the quantum context, Green's functions are correlation functions, from which it is possible…

Mesoscale and Nanoscale Physics · Physics 2016-10-14 Mariana M. Odashima , Beatriz G. Prado , E. Vernek

In this paper, we show that a nonequilibrium steady state (NESS) exists at late times in open quantum systems with weak nonlinearity by following its nonequilibrium dynamics with a perturbative analysis. Here we consider an oscillator chain…

Quantum Physics · Physics 2020-09-14 Jing Yang , Jen-Tsung Hsiang , Andrew N. Jordan , B. L. Hu

Non-equilibrium Green's functions provide an efficient way to describe the evolution of the energy-momentum tensor during the early time pre-equilibrium stage of high-energy heavy ion collisions. Besides their practical relevance they also…

High Energy Physics - Phenomenology · Physics 2020-09-09 Syo Kamata , Mauricio Martinez , Philip Plaschke , Stephan Ochsenfeld , S. Schlichting

Modeling a high-dimensional Hamiltonian system in reduced dimensions with respect to coarse-grained (CG) variables can greatly reduce computational cost and enable efficient bottom-up prediction of main features of the system for many…

Computational Engineering, Finance, and Science · Computer Science 2021-04-09 Shu Wang , Zhan Ma , Wenxiao Pan

Simulations of quantum transport in coherent conductors have evolved into mature techniques that are used in fields of physics ranging from electrical engineering to quantum nanoelectronics and material science. The most efficient…

Mesoscale and Nanoscale Physics · Physics 2019-12-25 Mathieu Istas , Christoph Groth , Xavier Waintal

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

Nonequilibrium Green's functions represent underutilized means of studying the time evolution of quantum many-body systems. In view of a rising computer power, an effort is underway to apply the Green's functions formalism to the dynamics…

Nuclear Theory · Physics 2008-11-26 Arnau Rios , Pawel Danielewicz

Digital quantum simulation uses the capabilities of quantum computers to determine the dynamics of quantum systems, which are beyond the computability of modern classical computers. A notoriously challenging task in this field is the…

Quantum Physics · Physics 2021-04-19 Benedikt Fauseweh , Jian-Xin Zhu

Nonequilibrium electronic forces play a central role in voltage-driven phase transitions but are notoriously expensive to evaluate in dynamical simulations. Here we develop a machine learning framework for adiabatic lattice dynamics coupled…

Strongly Correlated Electrons · Physics 2026-01-13 Yunhao Fan , Sheng Zhang , Gia-Wei Chern

The exact quantum dynamics of lattice models can be computationally intensive, especially when aiming for large system sizes and extended simulation times necessary to converge transport coefficients. By leveraging finite memory times to…

Chemical Physics · Physics 2024-11-14 Srijan Bhattacharyya , Thomas Sayer , Andrés Montoya-Castillo

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

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

The non-equilibrium Green's function method combined with density functional theory (NEGF-DFT) provides a rigorous framework for simulating nanoscale electronic transport, but its computational cost scales steeply with system size. Recent…

Mesoscale and Nanoscale Physics · Physics 2025-10-21 Zili Tang , Xiaoxin Xie , Guanwen Yao , Ligong Zhang , Xiaoyan Liu , Xing Zhang , Liu Fei