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We present a new approach to derive the connectivity properties of pairwise interacting n-body systems in thermal equilibrium. We formulate an integral equation that relates the pair connectedness to the distribution of nearest neighbors.…

Statistical Mechanics · Physics 2020-07-01 Fabian Coupette , Andreas Härtel , Tanja Schilling

We demonstrate that a numerical linked cluster expansion method is a powerful tool to calculate quantum dynamics. We calculate the dynamics of the magnetization and spin correlations in the two-dimensional transverse field Ising and XXZ…

Quantum Physics · Physics 2021-06-03 Ian G. White , Bhuvanesh Sundar , Kaden R. A. Hazzard

We present a coupled pair approach for studying few-body physics in harmonically trapped ultracold gases. The method is applied to a two-component Fermi system of $N$ particles. A stochastically variational gaussian expansion method is…

Quantum Gases · Physics 2014-08-27 C. J. Bradly , B. C. Mulkerin , A. M. Martin , H. M. Quiney

We establish the exponential clustering of correlation functions for the high-temperature Gibbs states of Bose-Hubbard type models. To overcome the technical difficulties arising from the unboundedness of bosonic operators, we develop the…

Statistical Mechanics · Physics 2026-03-31 Xin-Hai Tong , Tomotaka Kuwahara , Zongping Gong

Highly size-asymmetrical fluid mixtures arise in a variety of physical contexts, notably in suspensions of colloidal particles to which much smaller particles have been added in the form of polymers or nanoparticles. Conventional schemes…

Soft Condensed Matter · Physics 2011-01-14 Douglas J. Ashton , Jiwen Liu , Erik Luijten , Nigel B. Wilding

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…

Quantum Monte Carlo (QMC) methods are one of the most important tools for studying interacting quantum many-body systems. The vast majority of QMC calculations in interacting fermion systems require a constraint to control the sign problem.…

Strongly Correlated Electrons · Physics 2016-12-08 Mingpu Qin , Hao Shi , Shiwei Zhang

We provide a pedagogical introduction to numerical linked-cluster expansions (NLCEs). We sketch the algorithm for generic Hamiltonians that only connect nearest-neighbor sites in a finite cluster with open boundary conditions. We then…

Statistical Mechanics · Physics 2013-03-13 Baoming Tang , Ehsan Khatami , Marcos Rigol

A full coupled-cluster expansion suitable for sparse algebraic operations is developed by expanding the commutators of the Baker-Campbell-Hausdorff series explicitly for cluster operators in binary representations. A full coupled-cluster…

Chemical Physics · Physics 2018-09-13 Enhua Xu , Motoyuki Uejima , Seiichiro L. Ten-no

By introducing a set of auxiliary equations representing a many-body system, we have derived an extension of the Kohn-Sham scheme for the density functional theory. These equations consist of a Kohn-Sham-type equation determining…

Materials Science · Physics 2009-11-07 Koichi Kusakabe

We adapt the Coupled Cluster Method to solid state strongly correlated lattice Hamiltonians extending the Coupled Cluster linear response method to the calculation of electronic spectra and obtaining the space-time Fourier transforms of…

Strongly Correlated Electrons · Physics 2017-02-16 Alessandro Mirone

We employ \textit{ab initio} methods of quantum chemistry to investigate spin-1/2 fermions interacting via a two-body contact potential in a one-dimensional harmonic trap. The convergence of the total energy with the size of the…

I discuss how a variatonal approach can be extended to systems of identical particles (in particular fermions) within the path-integral treatment. The applicability of the many-body variational principle for path integrals is illustrated…

Strongly Correlated Electrons · Physics 2016-11-23 J. T. Devreese

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

Multicomponent systems are defined as chemical systems that require a quantum mechanical description of two or more different types of particles. Non-Born-Oppenheimer electron-nuclear interactions in molecules, electron-hole interactions in…

Chemical Physics · Physics 2015-10-21 Benjamin H. Ellis , Somil Aggarwal , Arindam Chakraborty

We analyze the tensor network loop cluster expansion, introduced in [G. Park, J. Gray, and G. K.-L. Chan, Phys. Rev. B 112, 174310 (2025)] as a systematic correction to belief propagation, in the context of general quantum many-body…

Inspired by recent experiments on many-body localized systems coupled to an environment, we apply a Flow Equation method to study the problem of a disorder chain of spinless fermions, coupled via density-density interactions to a second…

Disordered Systems and Neural Networks · Physics 2020-01-16 Shane P. Kelly , Rahul Nandkishore , Jamir Marino

An effective method based on Hubbard-Schofield approach [Phys. Lett. A {\bf 40}, 245 (1972)] is developed to calculate the free energy of classical Coulomb systems. This method significantly simplifies the derivation of the cluster…

Classical Physics · Physics 2007-05-23 J. Ortner

A two-component system of penetrable particles interacting via a gaussian core potential is considered, which may serve as a crude model for binary polymer solutions. The pair structure and thermodynamic properties are calculated within the…

Soft Condensed Matter · Physics 2007-05-23 R. Finken , J. -P. Hansen , A. A. Louis

Introducing low-energy effective Hamiltonians is usual to grasp most correlations in quantum many-body problems. For instance, such effective Hamiltonians can be treated at the mean-field level to reproduce some physical properties of…

Quantum Gases · Physics 2025-01-09 Raphaël Photopoulos , Antoine Boulet