Hello, A new project on the LCRC cluster has been requested. Please forward the information on to the LCRC Allocation sub-committee. Applicant's name: Zeke Insepov Applicant's institution: ANL Applicant's division: MCS Project Name: xenon Project title: Ab-initio simulation of bubbles in dense media Associated funding: RERTR Other Systems: Blue Gene Science: Summary of the project: Fission gases form small bubbles in nuclear fuels that leads to lattice swelling and cracking. Our simulation will be useful for understanding this phenomenon. In collaboration with the colleagues from Russian Academy of Sciences, Dr. Zeke Insepov of Argonne National Laboratory are working on developing a new interatomic potential for the following metal fuels: Mo-Xe, Mo-U. The aim of the project is to provide molecular dynamics of the evolution of radiation-induced defects with the interatomic potentials verified by ab initio calculations and available experimental data on the properties of the defects (the latter are very limited). The major idea of the project is to take into account the data on per-atom forces and energies (from ab initio calculations) of the configurations with basic types of radiation defects in order to describe correctly the potential surface for their diffusion. Moreover, the force-matching method involved gives a possibility to consider the forces on atoms in different neighboring, including configurations in thermal motion at various densities. Project 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. Project URL: Requested allocation: 3000000 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). The requester has used 0 hours of their initial startup project. In addition to approving an initial amount, please specify a Category and Subcategory for this project. For a list of the current selection of approved categories, please see: https://wiki.lcrc.anl.gov/wiki/Processes/Categories Once the Allocation committee has approved the project, please go to the Project Management page to create it: https://accounts.lcrc.anl.gov/projects.php Thank You, The LCRC Accounts System