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The binding energies and proton separation energies of nuclides with $Z, N = 30-50$ are investigated, based on the shell model with an uncertainty analysis through statistical methods. Several formulas are used to obtain the binding…

Nuclear Theory · Physics 2022-05-06 Boshuai Cai , Guangshang Chen , Cenxi Yuan , Jianjun He

We explore the application of an extrapolative method that yields very accurate total and relative energies from variational and diffusion quantum Monte Carlo (VMC and DMC) results. For a trial wave function consisting of a small…

Computational Physics · Physics 2024-04-25 Seyed Mohammadreza Hosseini , Ali Alavi , Pablo Lopez Rios

We introduce spin projection methods in the shell model Monte Carlo approach and apply them to calculate the spin distribution of level densities for iron-region nuclei using the complete $(pf+g_{9/2})$-shell. We compare the calculated…

Nuclear Theory · Physics 2008-11-26 Y. Alhassid , S. Liu , H. Nakada

The shell model Monte Carlo (SMMC) approach provides a powerful method for the microscopic calculation of statistical and collective nuclear properties in model spaces that are many orders of magnitude larger than those that can be treated…

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

A method of truncating the large shell model basis is outlined. It relies on the order given by the unperturbed energies of the basis states and on the constancy of their spreading widths. Both quantities can be calculated by a simple…

Nuclear Theory · Physics 2009-09-25 Mihai Horoi , B. Alex Brown , Vladimir Zelevinsky

A variational approach, based on a discrete representation of the chain, is used to calculate free energy and conformational properties in polyelectrolytes. The true bond and Coulomb potentials are approximated by a trial isotropic harmonic…

chem-ph · Physics 2016-08-15 B. Jönsson , C. Peterson , B. Söderberg

We present a simple and powerful method for extrapolating finite-volume Monte Carlo data to infinite volume, based on finite-size-scaling theory. We discuss carefully its systematic and statistical errors, and we illustrate it using three…

High Energy Physics - Lattice · Physics 2009-10-28 Sergio Caracciolo , Robert G. Edwards , Sabino J. Ferreira , Andrea Pelissetto , Alan D. Sokal

We present a Monte Carlo method to compute efficiently susceptibilites or covariances of two physical variables. The method relies on a generalization of the exchange cluster algorithm to any model of interacting particles with any $2$-body…

Computational Physics · Physics 2025-02-11 Assaraf Roland , Chevreau Hilaire

We present novel Monte Carlo methods for treating the interacting shell model that allow exact calculations much larger than those heretofore possible. The two-body interaction is linearized by an auxiliary field; Monte Carlo evaluation of…

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

Monte Carlo evaluation is used to calculate heavy-ion elastic scattering including the center-of-mass correction and the Coulomb interaction.Angular distributions are presented for a number of nuclear pairs over a wide energy range using…

Nuclear Theory · Physics 2015-06-04 W. R. Gibbs , Jean-Pierre Dedonder

We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; the…

Nuclear Theory · Physics 2009-10-30 S. E. Koonin , D. J. Dean , K. Langanke

Calculations of nuclei are often carried out in finite model spaces. Thus, finite-size corrections enter, and it is necessary to extrapolate the computed observables to infinite model spaces. In this work, we employ extrapolation methods…

Nuclear Theory · Physics 2019-11-25 W. G. Jiang , G. Hagen , T. Papenbrock

Using a new analytic quantum mechanical method based on Slater's Xalpha method, we show that a fairly accurate estimate of the total energy of a molecule can be obtained from the exact energies of its constituent atoms. The mean absolute…

Materials Science · Physics 2009-11-11 Rajendra R. Zope , Brett I. Dunlap

While the shell model Monte Carlo approach has been successful in the microscopic calculation of nuclear state densities, it has been difficult to calculate accurately state densities of odd-even heavy nuclei. This is because the projection…

Nuclear Theory · Physics 2013-04-30 C. Özen , Y. Alhassid , H. Nakada

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 uncertainty in the absolute value of the air-fluorescence yield still puts a severe limit on the accuracy in the primary energy of ultra-high-energy cosmic rays. The precise measurement of this parameter in laboratory is in turn…

Instrumentation and Methods for Astrophysics · Physics 2015-06-05 J. Rosado , P. Gallego , D. García-Pinto , F. Blanco , F. Arqueros

In Hybrid Monte Carlo(HMC) simulations for full QCD, the gauge fields evolve smoothly as a function of Molecular Dynamics (MD) time. Thus we investigate improved methods of estimating the trial solutions to the Dirac propagator as…

High Energy Physics - Lattice · Physics 2009-10-28 R. C. Brower , A. R. Levi , K. Orginos

We study Monte Carlo calculations of the effective potential for a scalar field theory using three techniques. One of these is a new method proposed and tested for the first time. In each case we extract the renormalised quantities of the…

High Energy Physics - Lattice · Physics 2010-03-04 A. Ardekani , A. G. Williams

We investigate the properties of two standard energy estimators used in path-integral Monte Carlo simulations. By disentangling the variance of the estimators and their autocorrelation times we analyse the dependence of the performance on…

Condensed Matter · Physics 2009-10-30 Wolfhard Janke , Tilman Sauer

The shapes of neutron-rich exotic Ni isotopes are studied. Large-scale shell model calculations are performed by advanced Monte Carlo Shell Model (MCSM) for the $pf$-$g_{9/2}$-$d_{5/2}$ model space. Experimental energy levels are reproduced…

Nuclear Theory · Physics 2015-06-17 Y. Tsunoda , T. Otsuka , N. Shimizu , M. Honma , Y. Utsuno