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We demonstrate the feasibility of realistic Shell-Model Monte Carlo (SMMC) calculations spanning multiple major shells, using a realistic interaction whose bad saturation and shell properties have been corrected by a newly developed general…

Nuclear Theory · Physics 2009-10-30 D. J. Dean , M. T. Ressell , M. Hjorth-Jensen , S. E. Koonin , K. Langanke , A. P. Zuker

We present a perspective on what the future holds for full configuration interaction (FCI) theory, with an emphasis on conceptual rather than technical details. Upon revisiting the early history of FCI, a number of its key contemporary…

Chemical Physics · Physics 2020-12-29 Janus J. Eriksen

We develop a quantum Monte Carlo method to estimate the ground-state energy of a fermionic many-particle system in the configuration-interaction shell model approach. The fermionic sign problem is circumvented by using a guiding wave…

Nuclear Theory · Physics 2015-06-15 Abhishek Mukherjee , Y. Alhassid

The mean-field approximation predicts pairing and shape phase transitions in nuclei as a function of temperature or excitation energy. However, in the finite nucleus the singularities of these phase transitions are smoothed out by quantal…

Nuclear Theory · Physics 2015-06-11 Y. Alhassid , C. Özen , H. Nakada

In this work, we present an overview of the phaseless auxiliary-field quantum Monte Carlo (ph- AFQMC) approach from a computational quantum chemistry perspective, and present a numerical assessment of its performance on main group chemistry…

Chemical Physics · Physics 2022-09-28 Joonho Lee , Hung Q. Pham , David R. Reichman

A novel machine learning approach is used to provide further insight into atomic nuclei and to detect orderly patterns amidst a vast data of large-scale calculations. The method utilizes a neural network that is trained on ab initio results…

Nuclear Theory · Physics 2022-03-14 O. M. Molchanov , K. D. Launey , A. Mercenne , G. H. Sargsyan , T. Dytrych , J. P. Draayer

We present Shell Model Monte Carlo calculations for nuclei within the full major shell 50-82 for both protons and neutrons. The interaction is determined solely by self-consistency and odd-even mass differences. The methods are illustrated…

Nuclear Theory · Physics 2009-01-23 Y. Alhassid , G. F. Bertsch , D. J. Dean , S. E. Koonin

Incremental full configuration interaction (iFCI) closely approximates the FCI limit with polynomial cost through a many-body expansion of the correlation energy, providing highly accurate total energies within a given basis set. To extend…

Chemical Physics · Physics 2025-02-26 Jeffrey Hatch , Paul M. Zimmerman

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

We introduce a fully antisymmetrized treatment of three-cluster dynamics within the ab initio framework of the no-core shell model/resonating-group method (NCSM/RGM). Energy-independent non-local interactions among the three nuclear…

Nuclear Theory · Physics 2013-10-23 S. Quaglioni , C. Romero-Redondo , P. Navrátil

The recently developed density matrix quantum Monte Carlo (DMQMC) algorithm stochastically samples the N -body thermal density matrix and hence provides access to exact properties of many-particle quantum systems at arbitrary temperatures.…

Strongly Correlated Electrons · Physics 2015-10-15 Fionn D. Malone , N. S. Blunt , James J. Shepherd , D. K. K. Lee , J. S. Spencer , W. M. C. Foulkes

Quantum Monte Carlo and semiclassical methods are used to solve two and four site cluster dynamical mean field approximations to the square lattice Hubbard model at half filling and strong coupling. The energy, spin correlation function,…

Strongly Correlated Electrons · Physics 2009-11-11 Andreas Fuhrmann , Satoshi Okamoto , Hartmut Monien , Andrew J. Millis

Nuclear level densities are crucial for estimating statistical nuclear reaction rates. The shell model Monte Carlo method is a powerful approach for microscopic calculation of state densities in very large model spaces. However, these state…

Nuclear Theory · Physics 2013-04-29 Y. Alhassid , M. Bonett-Matiz , S. Liu , H. Nakada

Emergent properties such as nuclear saturation and deformation, and the effects on shell structure due to the proximity of the scattering continuum and particle decay channels are fascinating phenomena in atomic nuclei. In recent years, ab…

Nuclear Theory · Physics 2016-05-19 G. Hagen , M. Hjorth-Jensen , G. R. Jansen , T. Papenbrock

The semistochastic heat-bath configuration interaction (SHCI) method is a selected configuration interaction plus perturbation theory method that has provided near-full configuration interaction (FCI) levels of accuracy for many systems…

Chemical Physics · Physics 2021-11-30 Yuan Yao , Emmanuel Giner , Tyler A. Anderson , Julien Toulouse , C. J. Umrigar

We present in detail a formulation of the shell model as a path integral and Monte Carlo techniques for its evaluation. The formulation, which linearizes the two-body interaction by an auxiliary field, is quite general, both in the form of…

Nuclear Theory · Physics 2008-11-26 G. H. Lang , C. W. Johnson , S. E. Koonin , W. E. Ormand

I describe the first continuous space nuclear path integral quantum Monte Carlo method, and calculate the ground state properties of light nuclei including Deuteron, Triton, Helium-3 and Helium-4, using both local chiral interaction up to…

Nuclear Theory · Physics 2022-07-19 Rong Chen

We report on the computational characteristics of ab initio nuclear structure calculations in a symmetry-adapted no-core shell model (SA-NCSM) framework. We examine the computational complexity of the current implementation of the SA-NCSM…

We report on the development of a new shell-model Monte Carlo algorithm which uses the proton-neutron formalism. Shell model Monte Carlo methods, within the isospin formulation, have been successfully used in large-scale shell-model…

Nuclear Theory · Physics 2015-06-26 C. Ozen , D. J. Dean

Using the \textit{ab initio} symmetry-adapted no-core shell model, we compute sum rules and response functions for light to medium-mass nuclei, starting from interactions that are derived in the chiral effective field theory. We investigate…

Nuclear Theory · Physics 2023-12-18 M. Burrows , R. B. Baker , S. Bacca , K. D. Launey , T. Dytrych , D. Langr
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