Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session H3: Frontiers in Computational Nuclear Physics |
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Sponsoring Units: DNP DCOMP Chair: Robert Tribble, Texas A&M University Room: Garden 3 |
Sunday, May 1, 2011 10:45AM - 11:21AM |
H3.00001: Ab initio methods for nuclear properties - a computational physics approach Invited Speaker: A microscopic theory for the structure and reactions of light nuclei poses formidable challenges for high-performance computing. Several ab-initio methods have now emerged that provide nearly exact solutions for some nuclear properties. The ab-initio no-core full configuration (NCFC) approach is based on basis space expansion methods and uses Slater determinants of single-nucleon basis functions to express the nuclear wave function. In this approach, the quantum many-particle problem becomes a large sparse matrix eigenvalue problem. The eigenvalues of this matrix give us the binding energies, and the corresponding eigenvectors the nuclear wave functions. These wave functions can be employed to evaluate experimental quantities. In order to reach numerical convergence for fundamental problems of interest, the matrix dimension often exceeds 1 billion, and the number of nonzero matrix elements may saturate available storage on present-day leadership class facilities. I discuss different strategies for distributing and solving this large sparse matrix on current multicore computer architectures, including methods to deal with with memory bottleneck. Several of these strategies have been implemented in the code MFDn, which is a parallel fortran code for nuclear structure calculations. I will show scaling behavior and compare the performance of the pure MPI version with the hybrid MPI/OpenMP code on Cray XT4 and XT5 platforms. For large core counts (typically 5,000 and above), the hybrid version is more efficient than pure MPI. With this code, we have been able to predict properties of the unstable nucleus 14F, which have since been confirmed by experiments. I will also give an overview of other recent results for nuclei in the A = 6 to 16 range with 2- and 3-body interactions. [Preview Abstract] |
Sunday, May 1, 2011 11:21AM - 11:57AM |
H3.00002: Lattice Gauge Theory Invited Speaker: Quantum Chromodynamcs (QCD) is now established as the theory of strong interactions. A plethora of hadronic physics phenomena can be explained and described by QCD. From the early days of QCD, it was clear that low energy phenomena require a non-perturbative approach. Lattice QCD is a non-perturbative formulation of QCD that is particularly suited for numerical calculations. However, it was obvious from the very beginning that enormous computer power is required to achieve results relevant to phenomenology. Today, in the era of petaflop computing, a significant stream of reliable results has been produced from Lattice QCD. I will review the most recent results, relevant to Nuclear Physics. In particular, I will focus on results for the spectrum, structure and interactions of hadrons, as well as discuss recent studies of QCD at non-zero temperature. Finally, I will comment on the opportunities opening up as we approach the era of exaflop computing. [Preview Abstract] |
Sunday, May 1, 2011 11:57AM - 12:33PM |
H3.00003: Modeling of Core-Collapse Supernovae Invited Speaker: Despite many decades of concerted theoretical effort and numerical modeling, the details of the core-collapse supernova explosion mechanism are still under debate. I review the current state of core-collapse supernova theory and highlight the recent progress made by multi-D hydrodynamic and neutrino-radiation-hydrodynamic core-collapse supernova models. I discuss how variations in the input nuclear and neutrino physics can effect the simulation outcome and the multi-messenger observational signature of core-collapse supernovae. [Preview Abstract] |
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