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The shell model Monte Carlo (SMMC) approach allows for the microscopic calculation of statistical and collective properties of heavy nuclei using the framework of the configuration-interaction shell model in very large model spaces. We…

Nuclear Theory · Physics 2015-06-23 C. Özen , Y. Alhassid , H. Nakada

We present extensive new \emph{ab initio} path integral Monte Carlo (PIMC) results for a variety of structural properties of warm dense hydrogen and beryllium. To deal with the fermion sign problem -- an exponential computational bottleneck…

The multilevel blocking algorithm recently proposed as a possible solution to the sign problem in path-integral Monte Carlo simulations has been extended to systems with long-ranged interactions along the Trotter direction. As an…

Chemical Physics · Physics 2009-11-06 R. Egger , L. Muehlbacher , C. H. Mak

The discrete time path integral Monte Carlo (PIMC) with a one-particle density matrix approximation is applied to study the quantum phase transition in the coupled double-well chain. To improve the convergence properties, the exact action…

Statistical Mechanics · Physics 2015-06-25 Dong-Hee Kim , Yu-Cheng Lin , Heiko Rieger

The shell model Monte Carlo (SMMC) method is a powerful method for calculating exactly (up to statistical errors) thermal observables and statistical properties of atomic nuclei. However, its application has been limited by a sign problem…

Nuclear Theory · Physics 2025-01-08 Y. Alhassid , P. Fanto , C. Özen

Being motivated by the surge of fermionic quantum Monte Carlo simulations at finite temperature, we present a detailed analysis of the permutation-cycle properties of path integral Monte Carlo (PIMC) simulations of degenerate electrons.…

Computational Physics · Physics 2019-07-24 Tobias Dornheim , Simon Groth , Alexei Filinov , Michael Bonitz

We study a trapped system of fermions with a zero-range two-body interaction using the shell-model Monte Carlo method, providing {\em ab initio} results for the low particle number limit where mean-field theory is not applicable. We present…

Superconductivity · Physics 2009-09-22 N. T. Zinner , K. Mølmer , C. Özen , D. J. Dean , K. Langanke

We present the first auxiliary field Monte Carlo calculations for a rare earth nucleus, Dy-170. A pairing plus quadrupole Hamiltonian is used to demonstrate the physical properties that can be studied in this region. We calculate various…

Nuclear Theory · Physics 2016-09-08 D. J. Dean , S. E. Koonin , G. H. Lang , P. B. Radha , W. E. Ormand

We use the Path Integral Monte Carlo method to investigate the interplay between shell effects and electron correlations in single quantum dots with up to 12 electrons. By use of an energy estimator based on the hypervirial theorem of…

Statistical Mechanics · Physics 2009-02-05 Jens Harting , Oliver Muelken , Peter Borrmann

Variational Monte Carlo and Green's function Monte Carlo are powerful tools for calculations of properties of light nuclei using realistic two-nucleon and three-nucleon potentials. Recently the GFMC method has been extended to multiple…

Nuclear Theory · Physics 2009-11-10 Steven C. Pieper

The behavior of the one-dimensional random-force-driven Burgers equation is investigated in the path integral formalism on a discrete space-time lattice. We show that by means of Monte Carlo methods one may evaluate observables, such as…

High Energy Physics - Lattice · Physics 2010-11-05 P. Düben , D. Homeier , K. Jansen , D. Mesterhazy , G. Münster

Monte Carlo simulations are useful tools for modeling quantum systems, but in some cases they suffer from a sign problem, leading to an exponential slow down in their convergence to a value. While solving the sign problem is generically…

Quantum Physics · Physics 2022-12-21 T. C. Mooney , Jacob Bringewatt , Neill C. Warrington , Lucas T. Brady

A new Quantum Monte-Carlo (QMC) approach is proposed to investigate low-lying states of nuclei within the shell model. The formalism relies on a variational symmetry-restored wave-function to guide the underlying Brownian motion. Sign/phase…

Nuclear Theory · Physics 2015-10-20 Jérémy Bonnard , Olivier Juillet

In this work we introduce a worldline based fermion Monte Carlo algorithm for studying few body quantum mechanics of self-interacting fermions in the Hamiltonian lattice formulation. Our motivation to construct the method comes from our…

Nuclear Theory · Physics 2025-02-28 Shailesh Chandrasekharan , Son T. Nguyen , Thomas R. Richardson

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

Quantum Monte Carlo methods have recently been employed to study properties of nuclei and infinite matter using local chiral effective field theory interactions. In this work, we present a detailed description of the auxiliary field…

Nuclear Theory · Physics 2018-05-02 D. Lonardoni , S. Gandolfi , J. E. Lynn , C. Petrie , J. Carlson , K. E. Schmidt , A. Schwenk

Quantum Monte Carlo (QMC) methods offer exact solutions for quantum many-body systems but face severe limitations in fermionic systems like atomic nuclei due to the sign problem. While sign-problem-free QMC algorithms exist and provide…

Nuclear Theory · Physics 2026-01-06 Zhong-Wang Niu , Bing-Nan Lu

Quantum Monte Carlo methods are sophisticated numerical techniques for simulating interacting quantum systems. In some cases, however, they suffer from the notorious "sign problem" and become too inefficient to be useful. A recent…

Strongly Correlated Electrons · Physics 2008-05-16 K. S. D. Beach , Matthieu Mambrini , Fabien Alet

We examine the application of the Variational Monte Carlo (VMC) method to a cluster model for halo nuclei. Particular attention is paid to the error estimate in the presence of correlations in the underlying random walk. We analyse the…

Nuclear Theory · Physics 2009-11-10 Theodoros Leontiou , Niels R. Walet

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