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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… (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)

- W. E. Ormand
- 2008

Isospin-mixing corrections for superallowed Fermi transitions in fp-shell nuclei are computed within the framework of the shell model. The study includes three nuclei that are part of the set of nine accurately measured transitions as well as five cases that are expected to be measured in the future at radioactive-beam facilities. We also include some new… (More)

- Jameel-Un Nabi, Calvin W Johnson, W Erich Ormand
- 2001

Nucleosynthesis calculations require nuclear level densities for hundreds or even thousands of nuclides. Ideally one would like to constrain these level densities by microscopically motivated yet computationally cheap models. A statistical approach suggests that low moments of the Hamiltonian might be sufficient. Recently Zuker proposed a simple… (More)

- Fe Y Alhassid, D J Dean, S E Koonin, G Lang, W E Ormand, W K Kellogg
- 1993

We present a practical solution to the " sign problem " in the auxiliary field Monte Carlo approach to the nuclear shell model. The method is based on extrapolation from a continuous family of problem-free Hamiltonians. To demonstrate the resultant ability to treat large shell-model problems, we present results for 54 Fe in the full f p-shell basis using… (More)

- W. E. Ormand
- 1998

The effects of isospin-symmetry breaking on the observables for parity-violating electron scattering are investigated within the framework of the nuclear shell model for 12 C, 16 O, and 28 Si. Contributions due to mixing with low-lying states as well as admixtures of 1p − 1h configurations (via the radial wave functions) are accounted for. It is found that… (More)

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