Using and Extending Two Newly Developed Multi-scale Modeling Methods to Study Novel Nano-Device Operation

As sizes decrease, surface interactions take on a more important role in nanometer-scale systems, to the point where they can induce interesting behaviors. The challenge is to develop simple,

representative mathematical models of the fundamental components that will be used to advance nanotechnology. The PIs have successfully developed two new modeling methods. One seamlessly merges atomic- scale molecular dynamics with finite-element treatments and allows regions of a model to be adaptively refined or coarsened during a simulation. The other uses two displacement fields to capture

important effects in nanotechnology missed by traditional models. We will build from this new foundation to: 1) refine, extend, and enhance our modeling tools to incorporate such things as structure/

fluid interactions, which not only are ubiquitous at this size scale, but enable a new range of future device applications; and 2) characterize fundamental modes of surface-mediated device operation

at the nanometer scale.

At the ultimate limit of a structure nanometers in size, essentially every atom could be at the surface, particularly in carbon-based structures which have two-dimensional lattices. These systems are an

ideal ground for designing, simulating and testing new device concepts. While most engineers developing micro-electromechanical systems consider surface and interfacial interactions such as

friction to be a problem, the PIs will use them to advance nanotechnology. For example, the PIs will study surface interactions and lattice registry as ways to generate tunable nanometer scale motion to enable such things as electrically or thermally switchable nano-syringes. They will also explore the bistability of nanotubes which collapse into nanoribbons to develop nano-pumps, vices, switches and interconnected networks with unique mechanical properties.