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The recently introduced coupled cluster (CC) downfolding techniques for reducing the dimensionality of quantum many-body problems recast the CC formalism in the form of the renormalization procedure allowing, for the construction of…

Quantum Physics · Physics 2021-11-08 Nicholas P. Bauman , Karol Kowalski

Many quantal many-body methods that aim at the description of self-bound nuclear or mesoscopic electronic systems make use of auxiliary wave functions that break one or several of the symmetries of the Hamiltonian in order to include…

Nuclear Theory · Physics 2021-02-16 Benjamin Bally , Michael Bender

The ongoing progress in (nuclear) many-body theory is accompanied by an ever-rising increase in complexity of the underlying formalisms used to solve the stationary Schr\"odinger equation. The associated working equations at play in…

Nuclear Theory · Physics 2020-02-13 Alexander Tichai , Roland Wirth , Julien Ripoche , Thomas Duguet

The formation of angulon, stemming from the rotor (molecule or impurity) rotating in the quantum many-body field, adds a new member in the quasiparticle's family and has aroused intensively interests in multiple research fields. However,…

Mesoscale and Nanoscale Physics · Physics 2023-05-08 Yi-Yan Liu , Yu Cui , Xiao-Zhe Zhang , Ran-Bo Yang , Zhi-Qing Li , Zi-Wu Wang

We present a novel approach to spin-adapted coupled cluster theory. This approach is based on the entanglement of an open-shell molecule with electrons in a non-interacting bath; together they form a closed-shell state. For the total…

Chemical Physics · Physics 2023-05-22 Sarai Dery Folkestad , Bendik Støa Sannes , Henrik Koch

We extend the spherical coupled-cluster ab initio method for open-shell nuclei where two nucleons are removed from a shell subclosure. Following the recent implementation of the two-particle attached approach [Phys. Rev.C 110 (2024) 4,…

Nuclear Theory · Physics 2026-02-06 Francesco Marino , Francesca Bonaiti , Sonia Bacca , Gaute Hagen , Gustav R. Jansen

We develop a novel cluster expansion for finite-spin lattice systems subject to multi-body quantum -- and, in particular, classical -- interactions. Our approach is based on the use of ``decoupling parameters", advocated by Park [34], which…

Mathematical Physics · Physics 2023-07-21 Nguyen Tong Xuan , Roberto Fernandez

A new perturbative approach to canonical equation-of-motion coupled-cluster theory is presented using coupled-cluster perturbation theory. A second-order M{\o}ller-Plesset partitioning of the Hamiltonian is used to obtain the well known…

Chemical Physics · Physics 2015-07-09 Jason N. Byrd , Varun Rishi , Ajith Perera , Rodney J. Bartlett

In this tutorial-style review we discuss basic concepts of coupled cluster theory and recent developments that increase its computational efficiency for calculations of molecules, solids and materials in general. We will touch upon the…

Materials Science · Physics 2020-04-15 Igor Ying Zhang , Andreas Grüneis

Background: Ab initio many-body methods whose numerical cost scales polynomially with the number of particles have been developed over the past fifteen years to tackle closed-shell mid-mass nuclei. Open-shell nuclei have been further…

Nuclear Theory · Physics 2018-06-27 Julien Ripoche , Thomas Duguet , Jean-Paul Ebran , Denis Lacroix

Various applications of quantum algebraic techniques in nuclear structure physics, such as the su$_q$(2) rotator model and its extensions, the use of deformed bosons in the description of pairing correlations, and the construction of…

Nuclear Theory · Physics 2008-02-03 Dennis Bonatsos , C. Daskaloyannis , P. Kolokotronis , D. Lenis

A general algebraic approach, incorporating both invariance groups and dynamic symmetry algebras, is developed to reveal hidden coherent structures (closed complexes and configurations) in quantum many-body physics models due to symmetries…

Quantum Physics · Physics 2008-11-26 Valery P. Karassiov

The reach of ab initio many-body theories is rapidly extending over the nuclear chart. However, dealing fully with three-nucleon, possibly four-nucleon, interactions makes the solving of the A-body Schr\"odinger equation particularly…

Nuclear Theory · Physics 2020-03-18 Julien Ripoche , Alexander Tichai , Thomas Duguet

In this review, we present a symmetry-guided strategy that utilizes exact as well as partial symmetries for enabling a deeper understanding of and advancing ab initio studies for determining the microscopic structure of atomic nuclei. These…

Nuclear Theory · Physics 2016-12-14 Kristina D. Launey , Tomas Dytrych , Jerry P. Draayer

The many-body states in an extended Fermionic Molecular Dynamics approach are flexible enough to allow the description of nuclei with shell model nature as well as nuclei with cluster and halo structures. Different many-body configurations…

Nuclear Theory · Physics 2009-11-10 T. Neff , H. Feldmeier

To solve the relativistic bound-state problem one needs to systematically and simultaneously decouple the high-energy from the low-energy modes and the many-body from the few-particle states using a consistent renormalization scheme. In a…

High Energy Physics - Theory · Physics 2009-11-10 Amir H. Rezaeian , Niels R. Walet

Perturbative and non-perturbative expansion methods already constitute a tool of choice to perform ab initio calculations over a significant part of the nuclear chart. In this context, the categories of accessible nuclei directly reflect…

Nuclear Theory · Physics 2022-01-28 Mikael Frosini , Thomas Duguet , Jean-Paul Ebran , Vittorio Somà

Correlations play a crucial role in the nuclear many-body problem. We give an overview of recent developments in nuclear structure theory aiming at the description of these interaction-induced correlations by unitary transformations. We…

Nuclear Theory · Physics 2010-06-08 Robert Roth , Thomas Neff , Hans Feldmeier

Projected Hartree-Fock theory provides an accurate description of many kinds of strong correlations but does not properly describe weakly-correlated systems. On the other hand, single-reference methods such as configuration interaction or…

Strongly Correlated Electrons · Physics 2022-04-06 Ruiheng Song , Thomas M. Henderson , Gustavo E. Scuseria

We introduce a shell-model theory that combines traditional spherical states, which yield a diagonal representation of the usual single-particle interaction, with collective configurations that track deformations, and test the validity of…

Nuclear Theory · Physics 2009-11-07 V. G. Gueorguiev , W. E. Ormand , C. W. Johnson , J. P. Draayer