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We propose a new variational Monte Carlo (VMC) method with an energy variance extrapolation for large-scale shell-model calculations. This variational Monte Carlo is a stochastic optimization method with a projected correlated condensed…

Nuclear Theory · Physics 2012-02-14 Takahiro Mizusaki , Noritaka Shimizu

The energy variance extrapolation method consists in relating the approximate energies in many-body calculations to the corresponding energy variances and inferring eigenvalues by extrapolating to zero variance. The method needs a fast…

Nuclear Theory · Physics 2015-06-03 G. Puddu

An extrapolation method in shell model calculations with deformed basis is presented, which uses a scaling property of energy and energy variance for a series of systematically approximated wave functions to the true one. Such approximated…

Nuclear Theory · Physics 2009-11-10 Takahiro Mizusaki

We propose a new shell model method, combining the Lanczos digonalization and extrapolation method. This method can give accurate shell model energy from a series of shell model calculations with various truncation spaces, in a…

Nuclear Theory · Physics 2009-11-07 Takahiro Mizusaki , Masatoshi Imada

A second order extrapolation method is presented for shell model calculations, where shell model energies of truncated spaces are well described as a function of energy variance by quadratic curves and exact shell model energies can be…

Nuclear Theory · Physics 2009-11-10 Takahiro Mizusaki , Masatoshi Imada

Constructing more expressive ansatz has been a primary focus for quantum Monte Carlo, aimed at more accurate \textit{ab initio} calculations. However, with more powerful ansatz, e.g. various recent developed models based on neural-network…

Computational Physics · Physics 2023-08-07 Weizhong Fu , Weiluo Ren , Ji Chen

We discuss a variational calculation for nuclear shell-model calculations and propose a new procedure for the energy-variance extrapolation (EVE) method using a sequence of the approximated wave functions obtained by the variational…

We present a newly enhanced version of the Monte Carlo Shell Model method by incorporating the conjugate gradient method and energy-variance extrapolation. This new method enables us to perform large-scale shell-model calculations that the…

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

The feasibility of shell-model calculations is radically extended by the Quantum Monte Carlo Diagonalization method with various essential improvements. The major improvements are made in the sampling for the generation of shell-model basis…

Nuclear Theory · Physics 2008-11-26 Michio Honma , Takahiro Mizusaki , Takaharu Otsuka

Conventional diagonalization methods to calculate nuclear energy levels in the framework of the configuration-interaction (CI) shell model approach are prohibited in very large model spaces. The shell model Monte Carlo (SMMC) is a powerful…

Nuclear Theory · Physics 2025-01-08 Y. Alhassid , M. Bonett-Matiz , C. N. Gilbreth , S. Vartak

We perform an extrapolative analysis of "fast-growth" free-energy-difference (DF) estimates of a computer-modeled, fully-solvated ethane<->methanol transformation. The results suggest that extrapolation can greatly reduce the systematic…

Chemical Physics · Physics 2007-05-23 Daniel M. Zuckerman , Thomas B. Woolf

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

Nuclear many-body calculations are computationally demanding. An estimate of their accuracy is often hampered by the limited amount of computational resources even on present-day supercomputers. We provide an extrapolation method based on…

Nuclear Theory · Physics 2009-11-10 H. Zhan , A. Nogga , B. R. Barrett , J. P. Vary , P. Navratil

We investigate two kinds of extensions for the variational Monte Carlo (VMC) method with the Pfaffian in the nuclear shell-model calculations. One is the extension to odd-mass nuclei, for which we find a new Pfaffian expression of the VMC…

Nuclear Theory · Physics 2018-11-21 Noritaka Shimizu , Takahiro Mizusaki

We introduce a particle-number reprojection method in the shell model Monte Carlo that enables the calculation of observables for a series of nuclei using a Monte Carlo sampling for a single nucleus. The method is used to calculate nuclear…

Nuclear Theory · Physics 2009-10-31 Y. Alhassid , S. Liu , H. Nakada

We investigate an approximate sampling scheme that can significantly reduce the cost scaling of variational Monte Carlo when it is employed to predict the energy differences associated with local chemical changes. Inspired by side-chaining…

Chemical Physics · Physics 2026-03-13 Sonja Bumann , Eric Neuscamman

Monte-Carlo simulations are routinely used for estimating the scaling exponents of complex systems. However, due to finite-size effects, determining the exponent values is often difficult and not reliable. Here we present a novel technique…

Computational Physics · Physics 2013-03-05 Indrek Mandre , Jaan Kalda

The shell model Monte Carlo (SMMC) method enables calculations in model spaces that are many orders of magnitude larger than those that can be treated by conventional methods, and is particularly suitable for the calculation of level…

Nuclear Theory · Physics 2015-06-18 Y. Alhassid , M. Bonett-Matiz , S. Liu , A. Mukherjee , H. Nakada

The shell-model Monte Carlo (SMMC) technique transforms the traditional nuclear shell-model problem into a path-integral over auxiliary fields. We describe below the method and its applications to four physics issues: calculations of sdpf-…

Nuclear Theory · Physics 2009-10-31 D. J. Dean , J. A. White
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