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In this work, we developed an efficient approach to compute ensemble averages in systems with pairwise-additive energetic interactions between the entities. Methods involving full enumeration of the configuration space result in exponential…

Biomolecules · Quantitative Biology 2020-10-13 Arun V. Sathanur , Nathan A. Baker

We consider two distinct coupled cluster (CC) perturbation series that both expand the difference between the energies of the CCSD (CC with single and double excitations) and CCSDT (CC with single, double, and triple excitations) models in…

Chemical Physics · Physics 2016-02-17 Kasper Kristensen , Janus Juul Eriksen , Devin A. Matthews , Jeppe Olsen , Poul Jørgensen

A new state specific correlation correction to configuration interaction singles (CIS) excitation energies is preseted using coupled cluster perturbation theory (CCPT). General expressions for CIS-CCPT are derived and expanded explicitly to…

Chemical Physics · Physics 2015-06-19 Jason N. Byrd , Victor F. Lotrich , Rodney J. Bartlett

A coarse grid correction (CGC) approach is proposed to enhance the efficiency of the matrix exponential and $\varphi$ matrix function evaluations. The approach is intended for iterative methods computing the matrix-vector products with…

Numerical Analysis · Mathematics 2024-04-23 Mike A. Botchev

The short answer to the question in the title is 'no'. We identify classes of truncated configuration interaction (CI) wave functions for which the externally corrected coupled-cluster (ec-CC) approach using the three-body ($T_{3}$) and…

Chemical Physics · Physics 2021-08-24 Ilias Magoulas , Karthik Gururangan , Piotr Piecuch , J. Emiliano Deustua , Jun Shen

We introduce a novel class of coupled cluster (CC) methods that leverage the seniority concept to enhance efficiency and accuracy in electronic structure calculations. While existing approaches, such as the pair coupled cluster doubles…

The most essential concept in concurrent multiscale methods involving atomistic-continuum coupling is how to define the relation between atomistic and continuum regions. A well-known coupling method that has been frequently employed in…

Mesoscale and Nanoscale Physics · Physics 2022-07-27 Pouya Towhidi , Manouchehr Salehi

We develop a quartic-scaling implementation of coupled-cluster singles and doubles based on low-rank tensor hypercontraction (THC) factorizations of both the electron repulsion integrals (ERIs) and the doubles amplitudes. This extends our…

Chemical Physics · Physics 2024-06-19 Edward G. Hohenstein , B. Scott Fales , Robert M. Parrish , Todd J. Martinez

We present an excited-state-specific coupled-cluster approach in which both the molecular orbitals and cluster amplitudes are optimized for an individual excited state. The theory is formulated via a pseudoprojection of the traditional…

Chemical Physics · Physics 2023-11-27 Harrison Tuckman , Eric Neuscamman

Multi-agent systems (MASs) can autonomously learn to solve previously unknown tasks by means of each agent's individual intelligence as well as by collaborating and exploiting collective intelligence. This article considers a group of…

Systems and Control · Electrical Eng. & Systems 2021-11-29 Michael Meindl , Fabio Molinari , Dustin Lehmann , Thomas Seel

In recent years, a large number of genomic and epigenomic studies have been focusing on the integrative analysis of multiple experimental datasets measured over a large number of observational units. The objectives of such studies include…

Methodology · Statistics 2017-11-02 Chandler Zuo , Kailei Chen , Kyle Hewitt , Emery Bresnick , Sunduz Keles

We consider approximate dynamic programming in $\gamma$-discounted Markov decision processes and apply it to approximate planning with linear value-function approximation. Our first contribution is a new variant of Approximate Policy…

Machine Learning · Computer Science 2022-10-31 Gellért Weisz , András György , Tadashi Kozuno , Csaba Szepesvári

Strong correlation can be essentially captured with multireference wavefunction methods such as complete active space self-consistent field (CASSCF) or density matrix renormalization group (DMRG). Still, an accurate description of the…

Strongly Correlated Electrons · Physics 2022-04-06 Daria Drwal , Pavel Beran , Michał Hapka , Marcin Modrzejewski , Adam Sokół , Libor Veis , Katarzyna Pernal

Iterative learning control (ILC) improves the performance of a repetitive system by learning from previous trials. ILC can be combined with Model Predictive Control (MPC) to mitigate non-repetitive disturbances, thus improving overall…

Systems and Control · Electrical Eng. & Systems 2025-03-26 Riccardo Zuliani , Efe C. Balta , Alisa Rupenyan , John Lygeros

In recent years, machine-learning methods have become increasingly important for the experiments at the Large Hadron Collider (LHC). They are utilised in everything from trigger systems to reconstruction and data analysis. The recent…

We present a wide-reaching revamp of the generalized many-body expanded full configuration interaction (MBE-FCI) method. First, we outline how to automatize the selection of reference active spaces whereby the inherent bias introduced…

Chemical Physics · Physics 2024-06-18 Jonas Greiner , Jürgen Gauss , Janus J. Eriksen

Correlation clustering is a flexible framework for partitioning data based solely on pairwise similarity or dissimilarity information, without requiring the number of clusters as input. However, in many practical scenarios, these pairwise…

Machine Learning · Computer Science 2025-12-11 Linus Aronsson , Morteza Haghir Chehreghani

In a series of two articles, we propose a comprehensive mathematical framework for Coupled-Cluster-type methods. In this second part, we analyze the nonlinear equations of the single-reference Coupled-Cluster method using topological degree…

Numerical Analysis · Mathematics 2023-03-28 Mihály A. Csirik , Andre Laestadius

The efficiency of the recently proposed iCIPT2 [iterative configuration interaction (iCI) with selection and second-order perturbation theory (PT2); J. Chem. Theory Comput. 16, 2296 (2020)] for strongly correlated electrons is further…

Chemical Physics · Physics 2020-11-19 Ning Zhang , Wenjian Liu , Mark R. Hoffmann

The cluster-in-molecule (CIM) local correlation approach with an accurate distant pair correlation energy correction is presented. For large systems, the inclusion of distant pair correlation energies is essential for the accurate…

Chemical Physics · Physics 2020-08-06 Zhigang Ni , Yang Guo , Frank Neese , Wei Li , Shuhua Li
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