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Coupled-cluster (CC) theory and Green's function many-body perturbation theory (MBPT) have long evolved as distinct yet complementary frameworks for describing electronic correlation. While CC methods employ exponential wavefunction…

We introduce a new augmented adaptation of the recently developed full coupled-cluster reduction (FCCR) with a second-order perturbative correction, abbreviated as FCCR(2). FCCR is a selected coupled-cluster expansion aimed at optimally…

Chemical Physics · Physics 2020-11-06 Enhua Xu , Motoyuki Uejima , Seiichiro L. Ten-no

The development of numerical methods capable of simulating realistic materials with strongly correlated electrons, with controllable errors, is a central challenge in quantum many-body physics. Here we describe how a hybrid between…

Strongly Correlated Electrons · Physics 2015-04-23 Alexei A. Kananenka , Emanuel Gull , Dominika Zgid

Green's function methods within many-body perturbation theory provide a general framework for treating electronic correlations in excited states. Here we investigate the cumulant form of the one-electron Green's function based on the…

Chemical Physics · Physics 2021-04-23 F. D. Vila , J. J. Rehr , J. J. Kas , K. Kowalski , B. Peng

The iterative qubit coupled cluster (iQCC) method is a systematic variational approach to solve the electronic structure problem on universal quantum computers. It is able to use arbitrarily shallow quantum circuits at expense of iterative…

Quantum Physics · Physics 2020-09-30 Ilya G. Ryabinkin , Artur F. Izmaylov , Scott N. Genin

We present a modified model order reduction (MOR) technique for the FFT-based simulation of composite microstructures. It utilizes the earlier introduced MOR technique (Kochmann et al. [2019]), which is based on solving the…

Computational Engineering, Finance, and Science · Computer Science 2021-03-19 Christian Gierden , Johanna Waimann , Bob Svendsen , Stefanie Reese

We derive a low-scaling $G_0W_0$ algorithm for molecules, using pair atomic density fitting (PADF) and an imaginary time representation of the Green's function and describe its implementation in the Slater type orbital (STO) based Amsterdam…

Chemical Physics · Physics 2020-11-13 Arno Förster , Lucas Visscher

The pair-coupled-cluster doubles (pCCD) method has emerged as a viable approach for quantum-chemical studies of strongly correlated systems. Despite its lower formal scaling (O(N$^4$)) compared to other versions of coupled cluster (CC)…

Chemical Physics · Physics 2026-04-17 Rahul Chakraborty , Paweł Tecmer

The Green's function Monte Carlo (GFMC) method provides accurate solutions to the nuclear many-body problem and predicts properties of light nuclei starting from realistic two- and three-body interactions. Controlling the GFMC fermion-sign…

Nuclear Theory · Physics 2023-04-07 Gurtej Kanwar , Alessandro Lovato , Noemi Rocco , Michael Wagman

Balanced truncation is one of the most common model order reduction schemes. In this paper, we study finite-frequency model order reduction (FF-MOR) problems of linear continuous-time systems within the framework of balanced truncation…

Systems and Control · Computer Science 2017-03-21 Xin Du , Peter Benner

We extend the recently developed Quantum Quasi-Monte Carlo (QQMC) approach to obtain the full frequency dependence of Green functions in a single calculation. QQMC is a general approach for calculating high-order perturbative expansions in…

Strongly Correlated Electrons · Physics 2021-04-07 Corentin Bertrand , Daniel Bauernfeind , Philipp T. Dumitrescu , Marjan Maček , Xavier Waintal , Olivier Parcollet

A method based on separated integration to estimate anharmonic corrections to energy and vibration of molecules in a second-order diagrammatic vibrational many-body Green's function formalism has already been presented. A severe bottleneck…

Chemical Physics · Physics 2019-09-17 Prashant Rai , Khachik Sargsyan , Habib Najm , So Hirata

The ab initio description of the spectral interior of the absorption spectrum poses both a theoretical and computational challenge for modern electronic structure theory. Due to the often spectrally dense character of this domain in the…

Computational Engineering, Finance, and Science · Computer Science 2019-03-21 Roel Van Beeumen , David B. Williams-Young , Joseph M. Kasper , Chao Yang , Esmond G. Ng , Xiaosong Li

The Green-function technique, termed the irreducible Green functions (IGF) method, that is a certain reformulation of the equation-of motion method for double-time temperature dependent Green functions is presented. This method was…

Strongly Correlated Electrons · Physics 2007-05-23 A. L. Kuzemsky

Computation of the Green's function is crucial to study the properties of quantum many-body systems such as strongly correlated systems. Although the high-precision calculation of the Green's function is a notoriously challenging task on…

Quantifying uncertainties in physical or engineering systems often requires a large number of simulations of the underlying computer models that are computationally intensive. Emulators or surrogate models are often used to accelerate the…

Methodology · Statistics 2021-11-11 Junda Xiong , Xin Cai , Jinglai Li

With the increasing penetration of electronic loads and distributed energy resources (DERs), conventional load models cannot capture their dynamics. Therefore, a new comprehensive composite load model is developed by Western Electricity…

Systems and Control · Electrical Eng. & Systems 2020-05-18 Zixiao Ma , Zhaoyu Wang , Dongbo Zhao , Bai Cui

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

Despite recent advances, systematic quantitative treatment of the electron correlation problem in extended systems remains a formidable task. Systematically improvable Green's function methods capable of quantitatively describing weak and…

Chemical Physics · Physics 2016-11-15 Alexander A. Rusakov , Dominika Zgid

The second-order Green's function method (GF2) was shown recently to be an accurate self-consistent approach for electronic structure of correlated systems since the self-energy accounts for both the weak and some of the strong correlation.…

Chemical Physics · Physics 2016-03-31 Daniel Neuhauser , Roi Baer , Dominika Zgid