25 Tflop/s Multibillion-atom Molecular Dynamics Simulations and Visualization/analysis on Bluegene/l

We demonstrate the excellent performance and scalability of a classical molecular dynamics code, SPaSM, on the IBM BlueGene/L supercomputer at LLNL. Simulations involving up to 160 billion atoms (micron-size cubic samples) on 65,536 processors are reported, consistently achieving 24.4–25.5 Tflop/s for the commonly used Lennard-Jones 6-12 pairwise interaction potential. Two extended production simulations (one lasting 8 hours and the other 13 hours wall-clock time) of the shock compression and release of porous copper using a more realistic many-body potential are also reported, demonstrating the capability for sustained runs including on-the-fly parallel analysis and visualization of such massive data sets. This opens up the exciting new possibility of using atomistic simulations at micron length scales to directly bridge to mesoscale and continuum-level models.