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An open quantum system consists of leads connected to a device of interest. Within the nonequilibrium Green's function technique, we examine the replacement of leads by self-energies in continuum calculations. Our starting point is a…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Fredrick Michael , M. D. Johnson

This paper aims at introducing the formal foundations of the application of reduced density-matrix theory and Green's function theory to the analysis of molecular electronic transitions. For this sake, their mechanics, applied to specific…

Chemical Physics · Physics 2022-08-09 Thibaud Etienne

Problems of finite-temperature quantum statistical mechanics can be formulated in terms of imaginary (Euclidean) -time Green's functions and self-energies. In the context of realistic Hamiltonians, the large energy scale of the Hamiltonian…

Statistical Mechanics · Physics 2018-08-17 Emanuel Gull , Sergei Iskakov , Igor Krivenko , Alexander A. Rusakov , Dominika Zgid

The evaluation of elastodynamic Green's functions across numerous source-receiver locations, frequencies, and material properties, particularly in the context of parametric studies or boundary element computations, is computationally…

Numerical Analysis · Mathematics 2026-03-20 Zainab Farooq , Amar Pashov , Pieter Reumers , Stijn François , Geert Degrande

Many-body Green's functions encode all the properties and excitations of interacting electrons. While these are challenging to be evaluated accurately on a classical computer, recent efforts have been directed towards finding quantum…

We present a time-linear scaling method to simulate open and correlated quantum systems out of equilibrium. The method inherits from many-body perturbation theory the possibility to choose selectively the most relevant scattering processes…

Mesoscale and Nanoscale Physics · Physics 2025-06-10 R. Tuovinen , Y. Pavlyukh , E. Perfetto , G. Stefanucci

A numerical method is developed for calculating the real time Green's functions of very large sparse Hamiltonian matrices, which exploits the numerical solution of the inhomogeneous time-dependent Schroedinger equation. The method has a…

Computational Physics · Physics 2007-05-23 Toshiaki Iitaka

The pair distribution function (PDF) is a key quantity for the analysis of correlation effects of a quantum system both in equilibrium and far from equilibrium. We derive an expression for the PDF in terms of the single-particle Green's…

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

We study the radial flow of retarded Green's function of energy-momentum tensor and $R$-current of dual gauge theory in presence of generic higher derivative terms in bulk Lagrangian. These are first order non-linear Riccati equations. We…

High Energy Physics - Theory · Physics 2014-11-21 Nabamita Banerjee , Suvankar Dutta

Coupled-cluster and Green's function theories are highly successful in treating many-body electron correlation, and there has been significant interest in identifying and leveraging connections between them. Here we present a diagrammatic…

Strongly Correlated Electrons · Physics 2025-07-03 Christopher J. N. Coveney , David P. Tew

The key factor currently limiting the advancement of computational power of electronic computation is no longer the manufacturing density and speed of components, but rather their high energy consumption. While it has been widely argued…

Data Structures and Algorithms · Computer Science 2024-08-30 David Doty , Niels Kornerup , Austin Luchsinger , Leo Orshansky , David Soloveichik , Damien Woods

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

Theoretical descriptions of non equilibrium dynamics of quantum many-body systems essentially employ either (i) explicit treatments, relying on truncation of the expansion of the many-body wave function, (ii) compressed representations of…

Electron dynamics in a two-sites Hubbard model is studied using the nonequilibrium Green's function approach. The study is motivated by the empirical observation that a full solution of the integro-differential Kadanoff-Baym equation (KBE)…

Strongly Correlated Electrons · Physics 2024-01-23 Yaroslav Pavlyukh

Tensor contraction operations in computational chemistry consume significant fractions of computing time on large-scale computing platforms. The widespread use of tensor contractions between large multi-dimensional tensors in describing…

Distributed, Parallel, and Cluster Computing · Computer Science 2023-07-11 Erdal Mutlu , Ajay Panyala , Nitin Gawande , Abhishek Bagusetty , Jinsung Kim , Karol Kowalski , Nicholas Bauman , Bo Peng , Jiri Brabec , Sriram Krishnamoorthy

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

In this paper the Feynman Green function for Maxwell's theory in curved space-time is studied by using the Fock-Schwinger-DeWitt asymptotic expansion; the point-splitting method is then applied, since it is a valuable tool for regularizing…

General Relativity and Quantum Cosmology · Physics 2021-02-02 Roberto Niardi , Giampiero Esposito , Francesco Tramontano

Despite their simple intuition, convolutions are more tedious to analyze than dense layers, which complicates the transfer of theoretical and algorithmic ideas to convolutions. We simplify convolutions by viewing them as tensor networks…

Machine Learning · Computer Science 2024-10-25 Felix Dangel

This work presents a novel method for task optimization in industrial plants using quantum-inspired tensor network technology. This method obtains the best possible combination of tasks on a set of machines with directed constraints while…

We present a scalable tensor-based approach to computing input-normal/output-diagonal nonlinear balancing transformations for control-affine systems with polynomial nonlinearities. This transformation is necessary to determine the states…

Optimization and Control · Mathematics 2024-10-31 Nicholas A. Corbin , Arijit Sarkar , Jacquelien M. A. Scherpen , Boris Kramer