Hello, A change in allocation has been requested: Requester: wiringa (Robert Wiringa) Project: qmc_for_nuclei Title: Quantum Monte Carlo Calculations of Light Nuclei Description: In FY10 we did not make as much use of Fusion as expected - about 70,000 CPU hours total (counting early FY10 hours on Jazz as half-hours on Fusion), partly because we made 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, and it seems that the machine is getting shaky. In FY11 there will be three staff members and three postdocs working on the project. We would like to do the following: A) GFMC Nucleon-Nucleus Scattering We are continuing our studies of nucleon-nucleus scattering for n+3H, p+3He, n+4He, and p+4He, and for parity-violating (PV) n+4He scattering. Eventually we will continue to larger systems, but there are still some unresolved issues with the 3+1 and 4+1 scattering cases. Based on current experience with Fusion, we will need about 30,000 CPU hours to complete the present studies. B) 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, funded by a joint LDRD project. These studies show a surprising sensitivity to details of the nuclear Hamiltonian, in particular the three-body forces, which we need to explore further. A new postdoc is arriving this fall who will be studying meson-exchange-current contributions to magnetic moments and transitions in A=8-10 nuclei. We are also starting to provide transition densities in 9Be and 10B to help explain pion inelastic-scattering and new neutrino scattering data. For this work we expect to use 50,000 CPU hours in FY11. C) Unnatural-parity and double-intruder states We have been making GFMC calculations for the unnatural-parity excitations (where one nucleon is excited to the next nuclear shell) in 9Be and VMC calculations for unnatural-parity states in 10Be and 10B. We wish to continue this work in FY11, including double-intruder states in A=10 that have two nucleons excited to the next shell, and the parity-inversion in 11Be, where the 1/2+ intruder state is the ground state. Again, we wish to explore the sensitivity to different nuclear Hamiltonians, and estimate the need for 50,000 CPU hours in FY11. D) Neutron drops We will continue to use Auxiliary Field Diffusion Monte Carlo (AFDMC) and GFMC to compute properties of large systems of neutrons. These will be 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. Based on our work this past year, we estimate 30,000 hours for this work in FY11. 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 CPU's 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. We have already demonstrated that OpenMP also works well for us on Fusion for larger nuclei. This all adds up to 160,000 hours. Current: undetermined amount Justification: Requested: 16000 A specific reason has been given: We received only 80% of our requested allocation in October, and have used about 80% of that through the first two months of the FY. This addition would get us up to our original request and help us get through the next 3.5 months. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System