Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Robert Wiringa Project Name: qmc_for_nuclei Division: PHY Project title: Quantum Monte Carlo Calculations of Light Nuclei Associated funding: DOE Division of Nuclear Physics Other Systems: ANL Blue Gene/P (INCITE 15M hours for 12C studies) ANL Blue Gene/Q (early user time for same) ANL SiCortex (indeterminate) Science: This project uses Quantum Monte Carlo [Green's function (GFMC), variational (VMC), and auxiliary-field diffusion (AFDMC)] methods to compute ground-state and low-lying excited-state expectation values of energies, densities, structure functions, astrophysical reaction rates, etc., for light nuclei and low-energy scattering reactions involving these nuclei. Realistic two- and three-nucleon potentials are used. Our goal is a description of all of these systems using a Hamiltonian that also provides an excellent description of nucleon-nucleon scattering and nucleonic matter. Such a `standard nuclear model' can then be used, for example, to compute low-energy astrophysical reactions which cannot be experimentally measured. Project description: In FY11 we made fairly full use of our allotted Fusion time - about 160,000 cpu hours total. This is in addition to extensive use of the MCS SiCortex and ALCF Blue Gene for major parts of our research. We expect to continue using those other resources but the SiCortex time is not guaranteed. In FY12 there will be three staff members, one postdoc, and one or two external collaborators working on the project. We would like to do the following: A) Clustered wave functions for A=9-12 nuclei We have been making new variational Monte Carlo (VMC) wave functions for A=9-11 nuclei that reflect the inherent clustering in these nuclei in a fashion different from standard shell-model wave functions. These wave functions treat the natural and unnatural-parity states in these nuclei on a more equal footing and are making our first calculations of 11B and 11C possible. There are about eight states each in 10B and 10Be that need to be diagonalized and evaluated, as well as development of the A=11 nuclei, and we estimate a need for 100,000 cpu hours for this program in FY12. B) GFMC Nucleon-Nucleus Scattering We are continuing studies of nucleon-nucleus scattering for n+3H, p+3He, n+4He, and p+4He, and for parity-violating (PV) n+4He scattering using Green's function Monte Carlo (GFMC). There are important unresolved issues with the 3+1 and 4+1 scattering cases, particularly handling coupled channels (for 3+1) and absolute normalizations (for PV 4+1). Based on current experience with Fusion, we will need about 30,000 cpu hours to complete the present studies. C) Spectroscopic overlaps, asymptotic normalizations and widths We have been calculating VMC spectroscopic overlaps, for application to nucleon-knockout experiments and transfer reactions, for many years. We continue to provide new or improved overlaps to experimental groups both at Argonne and elsewhere and wish to continue using our newer cluster-type wave functions described above. In the past year we also developed new integral techniques for evaluating asymptotic normalization constants (ANCs) and single-nucleon widths of narrow particle-unstable states. This work led to three papers (one Physical Review Letter, one Physical Review C Rapid Communication, and one regular Physical Review C article) in the past year. We would like to extend this to alpha-particle ANCs and widths in the next year. For FY12 we estimate 40,000 cpu hours for this part of the project. D) Transitions in A=8-10 Nuclei We have been studying electromagnetic transitions in 10Be and 10C in collaboration with the PHY low-energy experimental group for some time. These studies show a surprising sensitivity to details of the nuclear Hamiltonian, in particular the three-body forces, which we need to explore further. We have recently begun testing the role of charge-symmetry breaking on these transitions, and also examining weak decays in this sector. Our current postdoc has been developing meson-exchange-current contributions to electromagnetic transition operators and we wish to start testing them in the A=8-10 nuclei. For this work we expect to use 40,000 cpu hours in FY12. E) Neutron drops We also continue to use Auxiliary Field Diffusion Monte Carlo (AFDMC) and GFMC to compute properties of large systems of neutrons. These are both neutron drops and neutron matter done in periodic boundary conditions. We have two tasks: 1) to provide guidance to the development of energy density functional theories as part of the UNEDF SciDAC, and 2) to test the effect of three-body forces, fitted to light nuclei, in neutron matter. A Physical Review Letter on this subject was published this year. We estimate 30,000 cpu hours for this work in FY12. This all adds up to 240,000 hours. Project URL: http://www.phy.anl.gov/theory/research/forces.html Current FY Hours Used: undetermined amount New FY Requested allocation: 240000 Q1: 60000 Q2: 60000 Q3: 60000 Q4: 60000 Justification: The Quantum Monte Carlo methods work very efficiently on parallel processors. We use MPI and see speed-up efficiencies better than 95% for up to 250 cpus on Fusion, with sustained speeds of 1.8 GFLOPS/cpu. Using ADLB and OpenMP on BG/P we have run efficiently on 130,000 processors. Thank You, The LCRC Accounts System