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- Calvin W. Johnson, W. Erich Ormand, Plamen G. Krastev
- Computer Physics Communications
- 2013

One approach for solving interactingmany-fermion systems is the configuration-interactionmethod, also sometimes called the interacting shell model, where one finds eigenvalues of the Hamiltonian in a manybody basis of Slater determinants (antisymmetrized products of single-particle wavefunctions). The resulting Hamiltonian matrix is typically very sparse,… (More)

The <i>configuration-interaction</i> (CI) method, long a popular approach to describe quantum many-body systems, is cast as a very large sparse matrix eigenpair problem with matrices whose dimension can exceed one billion. Such formulations place high demands on memory capacity and memory bandwidth --- two quantities at a premium today. In this paper, we… (More)

Recent developments in nuclear theory allow us to make a connection between quantum chromodynamics (QCD) and low-energy nuclear physics. First, chiral effective field theory (χEFT) provides a natural hierarchy to define two-nucleon (NN), three-nucleon (NNN), and even four-nucleon interactions. Second, ab initio methods have been developed capable to test… (More)

- Scott Bogner, Aurel Bulgac, +28 authors Stefan M. Wild
- Computer Physics Communications
- 2013

The UNEDF project was a large-scale collaborative effort that applied high-performance computing to the nuclear quantum many-body problem. UNEDF demonstrated that close associations among nuclear physicists, mathematicians, and computer scientists can lead to novel physics outcomes built on algorithmic innovations and computational developments. This review… (More)

- Pieter Maris, James P. Vary, Petr Navratil, W. Erich Ormand, Ho-Seok Nam, David J. Dean
- Physical review letters
- 2011

We report the microscopic origins of the anomalously suppressed beta decay of ¹⁴C to ¹⁴N using the ab initio no-core shell model with the Hamiltonian from the chiral effective field theory including three-nucleon force terms. The three-nucleon force induces unexpectedly large cancellations within the p shell between contributions to beta decay, which reduce… (More)

- G. F. Grinyer, Claes Svensson, +28 authors E. F. Zganjar
- 2005

High precision measurements of 26Na β− decay G. F. Grinyer,1,∗ C. E. Svensson,1 C. Andreoiu,1 A. N. Andreyev,2 R. A. E. Austin,3,† G. C. Ball,2 R. S. Chakrawarthy,2 P. Finlay,1 P. E. Garrett,1,2 G. Hackman,2 J. C. Hardy,4 B. Hyland,1 V. E. Iacob,4 K. A. Koopmans,3 W. D. Kulp,5 J. R. Leslie,6 J. A. Macdonald,2 A. C. Morton,2 W. E. Ormand,7 C. J. Osborne,2 C.… (More)

- Petr Navratil, Vesselin G. Gueorguiev, James P. Vary, W. Erich Ormand, Andreas Nogga
- Physical review letters
- 2007

Properties of finite nuclei are evaluated with two-nucleon (NN) and three-nucleon (NNN) interactions derived within chiral effective field theory. The nuclear Hamiltonian is fixed by properties of the A=2 system, except for two low-energy constants (LECs) that parametrize the short range NNN interaction, which we constrain with the A=3 binding energies. We… (More)

- Petr Navratil, W. Erich Ormand
- Physical review letters
- 2002

We present a qualitative improvement of the ab initio no-core shell model (NCSM) approach by implementing three-body interaction capability for p-shell nuclei. We report the first calculations using three-body effective interactions derived from realistic nucleon-nucleon potentials for 6Li, 8Be, and 10B and demonstrate that the use of three-body effective… (More)

We introduce a shell-model theory that combines traditional spherical states, which yield a diagonal representation of the usual single-particle interaction, with collective configurations that track deformations, and test the validity of this mixed-mode, oblique-basis shell-model scheme on Mg. The correct binding energy ~within 2% of the full-space result!… (More)

- Patricia E . Garrett, W. Erich Ormand, +10 authors Daniel D. Warner
- Physical review letters
- 2001

The ground state band in (46)Cr and the isospin T = 1 band in (46)V have been delineated up to Ipi = 10(+) (tentatively 12(+)). These observations complete the highest spin T = 1 isospin triplet known. Following the isobaric multiplet mass equation, a combination of level energies in (46)Cr, (46)Ti, and (46)V are taken to highlight the angular momentum… (More)