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We develop a time dependent second order Green's function theory (GF2) for calculating neutral excited states in molecules. The equation of motion for the lesser Green's function (GF) is derived within the adiabatic approximation to the…

Chemical Physics · Physics 2022-01-19 Wenjie Dou , Joonho Lee , David R. Reichman , Roi Baer , Eran Rabani

We explore the simplification of widely used meta-generalized-gradient approximation (mGGA) exchange-correlation functionals to the Laplacian level of refinement by use of approximate kinetic energy density functionals (KEDFs). Such…

Chemical Physics · Physics 2017-12-01 Daniel Mejia-Rodriguez , S. B. Trickey

To explore whether the density-functional theory non-equilibrium Green's function formalism (DFT-NEGF) provides a rigorous framework for quantum transport, we carried out time-dependent density functional theory (TDDFT) calculations of the…

Materials Science · Physics 2011-07-01 ChiYung Yam , Xiao Zheng , GuanHua Chen , Yong Wang , Thomas Frauenheim , Thomas A. Niehaus

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

The non-equilibrium quantum field dynamics is usually described in the closed-time-path formalism. The initial state correlations are introduced into the generating functional by non-local source terms. We propose a functional approach to…

High Energy Physics - Phenomenology · Physics 2008-11-26 Q. Wang , K. Redlich , H. Stöcker , W. Greiner

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

For orbital-free {\it ab initio} molecular dynamics, especially on systems in extreme thermodynamic conditions, we provide the first pseudo-potential-adapted generalized gradient approximation (GGA) functional for the non-interacting free…

Chemical Physics · Physics 2020-02-19 Kai Luo , Valentin V. Karasiev , S. B. Trickey

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 non-equilibrium Green's function gives access to one-body observables for quantum systems. Of particular interest are quantities such as density, currents, and absorption spectra which are important for interpreting experimental results…

Computational Physics · Physics 2025-05-02 Thomas Blommel , David J. Gardner , Carol S. Woodward , Emanuel Gull

We discuss utilization of kinetic schemes for description of open interacting systems, focusing on vibrational energy relaxation for an oscillator coupled to a nonequilibirum electronic bath. Standard kinetic equations with constant rate…

Mesoscale and Nanoscale Physics · Physics 2018-08-16 Abraham Nitzan , Michael Galperin

Non-equilibrium Greens function techniques (NEGF) combined with Density Functional Theory (DFT) calculations have become a standard tool for the description of electron transport through single molecule nano-junctions in the coherent…

Materials Science · Physics 2009-11-13 R. Stadler , V. Geskin , J. Cornil

Using non-equilibrium Green's functions combined with many-body perturbation theory, we have calculated steady-state densities and currents through short interacting chains subject to a finite electric bias. By using a steady-state…

Mesoscale and Nanoscale Physics · Physics 2016-04-18 Daniel Karlsson , Claudio Verdozzi

We study quantum entanglement and its relation to transport in a non-equilibrium interacting double dot system connected to electronic baths. The dynamical properties in the non-interacting regime are studied using an exact numerical…

Mesoscale and Nanoscale Physics · Physics 2019-11-26 Anirban Dey , Devendra Singh Bhakuni , Bijay Kumar Agarwalla , Auditya Sharma

We aim to provide engineers with an introduction to the non-equilibrium Green's function (NEGF) approach, which provides a powerful conceptual tool and a practical analysis method to treat small electronic devices quantum mechanically and…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 M. P. Anantram , M. S. Lundstrom , D. E. Nikonov

Gaussian models provide an excellent effective description of many quantum many-body systems ranging from condensed matter systems all the way to neutron stars. Gaussian states are common at equilibrium when the interactions are weak.…

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

We provide a systematic approach to compute different kinds of non-equilibrium Green's functions for open quantum systems which are essentially two-point correlation functions in time. We reveal that the definition of Green's functions…

Statistical Mechanics · Physics 2023-09-08 Katha Ganguly , Bijay Kumar Agarwalla

A quantum transport model incorporating spin scattering processes is presented using the non-equilibrium Green's function (NEGF) formalism within the self-consistent Born approximation. This model offers a unified approach by capturing the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Ahmet Ali Yanik , Gerhard Klimeck , Supriyo Datta

We present a generalized dynamical mean-field approach for the nonequilibrium physics of a strongly correlated system in the presence of a time-dependent external field. The Keldysh Green's function formalism is used to study the…

Strongly Correlated Electrons · Physics 2007-05-23 P. Schmidt , H. Monien

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