From Atom-Picoseconds to Centimeter-Years in Simulation and Experiment

The final report for a Laboratory Directed Research and Development project entitled, ''From Atom-Picoseconds to Centimeter-Years in Simulation and Experiment'' is presented. In this project, separate modeling methods at the atomic scale were used to bridge gaps in time and space with higher scales. For understanding of continuum mechanics quantities at various scales atomistic simulations that ranged from nanometers to microns were performed and experiments from centimeters to millimeters were performed. Certain continuum mechanical quantities were clearly defined as a function of size scale, for example, the yield stress. Several techniques were used to extend the time scale of simulations, including calculating prefactors and activation energies for diffusion events and mapping complex atomic motions onto more tractable lattice models. In the case of transport of small molecules in polymeric and nanoporous materials, new Monte Carlo methods for sampling transition rates were developed