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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

We propose and apply the finite-element discrete variable representation to express the nonequilibrium Green's function for strongly inhomogeneous quantum systems. This method is highly favorable against a general basis approach with regard…

Strongly Correlated Electrons · Physics 2013-05-29 K. Balzer , S. Bauch , M. Bonitz

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 employ Non-equilibrium Green's functions (NEGF) to describe the real-time dynamics of an adsorbate-surface model system exposed to ultrafast laser pulses. For a finite number of electronic orbitals, the system is solved exactly and…

Mesoscale and Nanoscale Physics · Physics 2016-05-04 E. Boström , M. Hopjan , A. Kartsev , C. Verdozzi , C. -O. Almbladh

We have recently proposed a Nonequilibrium Green's Function (NEGF) approach to include Auger decay processes in the ultrafast charge dynamics of photoionized molecules. Within the so called Generalized Kadanoff-Baym Ansatz the fundamental…

Other Condensed Matter · Physics 2018-10-17 F. Covito , E. Perfetto , A. Rubio , G. Stefanucci

In this contribution, we discuss the finite-element discrete variable representation (FE-DVR) of the nonequilibrium Green's function and its implications on the description of strongly inhomogeneous quantum systems. In detail, we show that…

Strongly Correlated Electrons · Physics 2015-05-14 Karsten Balzer , Sebastian Bauch , Michael Bonitz

We investigate the possibility to deduce momentum space properties from time-dependent density functional calculations. Electron and ion momentum distributions after double ionization of a model Helium atom in a strong few-cycle laser pulse…

Atomic Physics · Physics 2009-11-13 F. Wilken , D. Bauer

Due to their conceptual appeal and computational convenience, two-level systems (TLS) and their generalisations are often used to investigate nonlinear behavior in quantum optics, and to assess the applicability of theoretical methods. Here…

Quantum Physics · Physics 2023-12-22 Megha Gopalakrishna , Yaroslav Pavlyukh , Claudio Verdozzi

We have developed a time propagation scheme for the Kadanoff-Baym equations for general inhomogeneous systems. These equations describe the time evolution of the nonequilibrium Green function for interacting many-body systems in the…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Adrian Stan , Nils Erik Dahlen , Robert van Leeuwen

The accurate description of the non-linear response of many-electron systems to strong-laser fields remains a major challenge. Methods that bypass the unfavorable exponential scaling with particle number are required to address larger…

Time-dependent nonequilibrium Green's functions (TDNEGF) are shown to provide a flexible, effective tool for the description of quantum mechanical single particle scattering on a spatially localized, time-dependent potential. Focusing on…

Quantum Physics · Physics 2017-12-07 Peter Foldi

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

We discuss a method of solving the time dependent Schrodinger equation for atoms with two active electrons in a strong laser field, which we used in a previous paper [A. Scrinzi and B. Piraux, Phys. Rev. A 56, R13 (1997)] to calculate…

Atomic Physics · Physics 2014-05-19 Armin Scrinzi , Bernard Piraux

The ultrafast hole dynamics triggered by the photoexcitation of molecular targets is a highly correlated process even for those systems, like organic molecules, having a weakly correlated ground state. We here provide a unifying framework…

Chemical Physics · Physics 2021-07-21 Yaroslav Pavlyukh , Enrico Perfetto , Gianluca Stefanucci

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 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 multiconfigurational time-dependent Hartree-Fock equations are discussed and solved for a one-dimensional model of the Helium atom. Results for the ground state energy and two-particle density as well as the absorption spectrum are…

Quantum Physics · Physics 2015-03-13 D. Hochstuhl , S. Bauch , M. Bonitz

We have implemented time-propagation of the non-equilibrium Green function for atoms and molecules, by solving the Kadanoff-Baym equations within a conserving self-energy approximation. We here demonstrate the usefulnes of time-propagation…

Materials Science · Physics 2007-05-23 Nils Erik Dahlen , Robert van Leeuwen

Quantization of electrodynamics in curved space-time in the Lorenz gauge and with arbitrary gauge parameter makes it necessary to study Green functions of non-minimal operators with variable coefficients. Starting from the integral…

Mathematical Physics · Physics 2007-05-23 Giuseppe Bimonte , Enrico Calloni , Luciano Di Fiore , Giampiero Esposito , Leopoldo Milano , Luigi Rosa

The time-dependent variational principle is used to optimize the linear and nonlinear parameters of Gaussian basis functions to solve the time-dependent Schrodinger equation in 1 and 3 dimensions for a one-body soft Coulomb potential in a…

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