Reactive Nanosystems: Multimillion Atom Simulations of Nanostructured Materials and Processes

P. Vashishta
University of Southern California, US

Keywords: nanostructured devices

Summary:

Advanced materials and devices with nanometer grain/feature sizes are being developed to achieve higher strength and toughness in ceramic materials, and greater speeds in electronic devices. Below 100 nm, however, continuum description of materials and devices must be supplemented by atomistic descriptions. Current state of the art atomistic simulations involve multimillion to a few billion atoms. We use multimillion atom reactive molecular dynamics simulations to investigate critical issues in the area of structural and dynamical correlations, and reactive processes in nanostructured materials under extreme conditions. In this talk I will discuss two simulations: (1) Reactive molecular dynamics simulations of heated aluminum nanoparticles have been performed to study the fast oxidation reaction processes of the core (aluminum)-shell (alumina) nanoparticles and small complexes. (2) Hydrogen production by aluminum super atoms in water could provide a renewable energy cycle, if its reaction kinetics is accelerated. Quantum molecular dynamics simulation reveals rapid hydrogen production from water by an Al superatom consisting of a magic number of aluminum atoms, Aln (for instance, n = 12 or 17). We find a low activation-barrier mechanism, in which a pair of Lewis acid and base sites on the Aln surface preferentially catalyzes hydrogen production. This Research is supported by the US Department of Energy, National Science Foundation, Office of Naval Research.