Hello, A change in allocation has been requested: Requester: insepov (Zeke Insepov) Project: Bubble-2011 Title: Ab-initio simulation of bubbles in dense media Description: The following calculations will be performed for interatomic potentials Mo-Mo, Mo-Xe, U-U in the form of embedded atom method: 1. Choosing of ‘configuration set’ – the structures to be taken into account during fitting of the potential, calculations of energies and forces on atoms in this configurations from DFT by VASP. 2. Creating of the potential with the use of the ‘configuration set’ by means of force-matching software PotFit. 3. Verification of the potential obtained by comparison with the DFT data: formation energies of vacancies, self-interstitial atoms (SIA) and their clusters, energies of the basic structures of SIAs, their hierarchy. Numerous MD and DFT calculations, basically static, will be performed on this step. 4. Verification of the potential with the experimental data on diffusion of defects (diffusivities, threshold temperatures to induce long-range migration) and production of defects in radiation cascades (structure of the defects and sizes). One more possibility is the threshold energies of the primary knocked atom required to initiate the displacement cascade as a function of the direction angle of the primary atom. All this calculations are dynamic, molecular dynamics package LAMMPS will be used. 5.Improvement of the ‘configuration set’ to reduce the discrepancies revealed in 3 and 4. computational methods: Density Functional Molecular Dynamics simulations using the siesta method programming model: parallel experiments planned: molecular dynamics simulations software requirements: fortran compiler (e.g. openmpi) sizes of calculations run on and/or planned for LCRC or other systems: hundreds of picoseconds time scale MD simulations on 100-500 atoms systems expected number of project members: 6 We expect a total of 6 project members (two including a student from University of Illinois, and five staff members from Russian Academy of Sciences. Results of assessments are expected to lead to joint proposals to NSF, DoE (Office of Science, and NE), and DARPA. Current: undetermined amount Justification: We recently purchased a new software - vasp - that will be widely applied to nuclear fuel simulation. One of the applications of the vasp software is the new interatomic potential for the Molybdenum-Xenon system that has been recognized as a breakthrough achievement for the future metal fuel simulations. The size of the simulation box should vary from ~ 10^2 (PotFit) to 10^3 (VASP) or 10^7 (LAMMPS) depending on the size of defect cluster, to ensure there are no interactions with the periodic images via an associated stress fields. All the software involved demonstrates good parallel performance and scalability for the tasks described above. So the typical number of CPUs varies from tens to hundreds (VASP, PotFit) or thousands (LAMMPS). Requested: 3000000 A specific reason has been given: We recently purchased a new software - vasp - that will be widely applied to nuclear fuel simulation. One of the applications of the vasp software is the new interatomic potential for the Molybdenum-Xenon system that has been recognized as a breakthrough achievement for the future metal fuel simulations. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System