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We present a near-linear scaling formulation of the explicitly-correlated coupled-cluster singles and doubles with perturbative triples method (CCSD(T)$_{\overline{\text{F12}}}$) for high-spin states of open-shell species. The approach is…

Chemical Physics · Physics 2024-07-30 Ashutosh Kumar , Frank Neese , Edward F. Valeev

The Goldstone-Brueckner perturbation theory is extended to incorporate in a simple way correlations associated with large amplitude collective motions in nuclei. The new energy expansion making use of non-orthogonal vacua still allows to…

Nuclear Theory · Physics 2009-11-07 T. Duguet

A methodology for handling block-to-block coupling of nonconforming, multiblock summation-by-parts finite difference methods is proposed. The coupling is based on the construction of projection operators that move a finite difference grid…

Numerical Analysis · Mathematics 2021-06-03 Jeremy E. Kozdon , Lucas C. Wilcox

We report the development of a parallel FORTRAN code, RCCPAC, to solve the relativistic coupled-cluster equations for closed-shell and one-valence atoms and ions. The parallelization is implemented through the use of message passing…

Atomic Physics · Physics 2017-02-08 B. K. Mani , Siddhartha Chattopadhyay , D. Angom

Elastic-scattering phase shifts for four-nucleon systems are studied in an $ab$-$initio$ type cluster model in order to clarify the role of the tensor force and to investigate cluster distortions in low energy $d+d$ and $t+p$ scattering. In…

Nuclear Theory · Physics 2015-05-28 S. Aoyama , K. Arai , Y. Suzuki , P. Descouvemont , D. Baye

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

Roles of electron correlation effects in the determination of attachment energies, magnetic dipole hyperfine structure constants and electric dipole (E1) matrix elements of the low-lying states in the singly charged cadmium ion (Cd$^+$)…

Atomic Physics · Physics 2018-03-14 Cheng-Bin Li , Yan-Mei Yu , B. K. Sahoo

Cohesive energies for twelve cubic III-V semiconductors with zincblende structure have been determined using an ab-initio scheme. Correlation contributions, in particular, have been evaluated using the coupled-cluster approach with single…

Condensed Matter · Physics 2009-10-28 Beate Paulus , Peter Fulde , Hermann Stoll

The open-shell reference relativistic equation-of-motion coupled-cluster method within its four-component description is successfully implemented with the consideration of single- and double- excitation approximation. The one-body and…

Atomic Physics · Physics 2016-09-21 Himadri Pathak , Sudip Sasmal , Malaya K. Nayak , Nayana Vaval , Sourav Pal

A new class of spatially-coupled turbo-like codes (SC-TCs), dubbed generalized spatially coupled parallel concatenated codes (GSC-PCCs), is introduced. These codes are constructed by applying spatial coupling on parallel concatenated codes…

Information Theory · Computer Science 2022-02-25 Min Qiu , Xiaowei Wu , Jinhong Yuan , Alexandre Graell i Amat

The application of Glauber theory has been playing an increasingly important role with the study of unstable or exotic nuclei. Its adaptation to medium and high-energy nucleus-nucleus collisions is severely limited because one has to…

Nuclear Theory · Physics 2026-03-18 W. Horiuchi , Y. Suzuki , R. B. Wiringa

Although self-consistent multi-configuration methods have been used for decades to address the description of atomic and molecular many-body systems, only a few trials have been made in the context of nuclear structure. This work aims at…

Nuclear Theory · Physics 2016-02-02 C. Robin , N. Pillet , D. Peña Arteaga , J. -F. Berger

A numerically implementable Multi-scale Many-Body approach to strongly correlated electron systems is introduced. An extension to quantum cluster methods, it approximates correlations on any given length-scale commensurate with the strength…

Strongly Correlated Electrons · Physics 2012-01-04 C. Slezak , M. Jarrell , Th. Maier , J. Deisz

A novel implementation of the coupled-cluster singles and doubles (CCSD) approach is presented that is specifically tailored for the treatment of large, symmetric systems. It fully exploits Abelian point-group symmetry and the use of the…

Chemical Physics · Physics 2023-12-07 Tommaso Nottoli , Jürgen Gauss , Filippo Lipparini

Convergence properties of the variational cluster approach with respect to the variational parameter space, cluster size, and boundary conditions of the reference system are investigated and discussed for bosonic many-body systems.…

Strongly Correlated Electrons · Physics 2010-06-21 Michael Knap , Enrico Arrigoni , Wolfgang von der Linden

We propose a variable decomposition algorithm -greedy block coordinate descent (GBCD)- in order to make dense Gaussian process regression practical for large scale problems. GBCD breaks a large scale optimization into a series of small…

Machine Learning · Computer Science 2012-06-18 Liefeng Bo , Cristian Sminchisescu

We consider the use in quantum Monte Carlo calculations of two types of valence bond wave functions based on strictly localized active orbitals, namely valence bond self-consistent-field (VBSCF) and breathing-orbital valence bond (BOVB)…

Chemical Physics · Physics 2011-03-14 Benoît Braïda , Julien Toulouse , Michel Caffarel , C. J. Umrigar

Numerical utilities of the Contact Block Reduction (CBR) method in evaluating the retarded Green's function, are discussed for 3-D multi-band open systems that are represented by the atomic tight-binding (TB) and continuum k\cdotp (KP) band…

Mesoscale and Nanoscale Physics · Physics 2015-06-03 Hoon Ryu , Hong-Hyun Park , Mincheol Shin , Dragica Vasileska , Gerhard Klimeck

Sparse linear prediction methods suffer from decreased prediction accuracy when the predictor variables have cluster structure (e.g. there are highly correlated groups of variables). To improve prediction accuracy, various methods have been…

Machine Learning · Statistics 2022-02-03 Rebecca Marion , Johannes Lederer , Bernadette Govaerts , Rainer von Sachs

An implementation of coupled-cluster (CC) theory to treat atoms and molecules in finite magnetic fields is presented. The main challenges stem from the magnetic-field dependence in the Hamiltonian, or, more precisely, the appearance of the…

Chemical Physics · Physics 2015-09-02 Stella Stopkowicz , Jürgen Gauss , Kai K. Lange , Erik I. Tellgren , Trygve Helgaker