Cross-scale atomistic simulations of crystal plasticity

Predictions of crystal plasticity directly from the atomic motion have been regarded as unthinkable given the severe limits on time- and length-scale accessible to direct MD simulations. We will discuss our recent direct MD simulations of compressive straining of single crystals of Ta and Al. One of our simulations, Livermore BigBig (LBB) simulation, is by far the largest MD simulation ever performed: it generated a fully dynamic trajectory of over 2.1 billion atoms over 5 microseconds of simulated MD trajectory. LBB generated nearly 80 exabytes of recordable trajectory data only a tiny fraction of which was saved on disk in a highly compressed/post-processed form available for further analysis. As opposed to multiscale, LBB and other simulations of its magnitude can be regarded as cross-scale being sufficiently large to be statistically representative of collective action of dislocations resulting in macroscopic crystal flow and yet fully resolved to every atomic “jiggle and wiggle”. We will discuss new insights into physics of crystal plasticity brought about by our simulations and discuss challenges and strategies for on-the-fly learning on immense data generated in such simulations.