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

随着尺寸的减小，表面相互作用在纳米级系统中扮演着更重要的角色，以至于它们可以诱导出有趣的行为。挑战是开发简单、有代表性的基本组成部分的数学模型，这些基本组成部分将用于推动纳米技术的发展。PI已经成功地开发了两种新的建模方法。一种是将原子尺度的分子动力学与有限元处理无缝地结合在一起，并允许在模拟过程中自适应地细化或粗化模型的区域。另一种是使用两个位移场来捕捉传统模型所遗漏的纳米技术中的重要效应。我们将在这个新的基础上建立：1)改进、扩展和增强我们的建模工具，以纳入诸如结构/流体相互作用之类的东西，这些东西不仅在这种尺寸范围内无处不在，而且能够在未来的器件应用中实现新的范围；以及2)在纳米尺度上表征表面介导的器件操作的基本模式。在纳米尺寸的结构的极限尺寸下，基本上每个原子都可以在表面，特别是在具有二维晶格的碳基结构中。这些系统是设计、模拟和测试新设备概念的理想基础。虽然大多数开发微电子机械系统的工程师认为表面和界面相互作用(如摩擦)是一个问题，但PI将利用它们来推动纳米技术。例如，PI将研究表面相互作用和晶格注册，以此作为产生可调纳米级运动的方法，从而使诸如电或热可切换纳米注射器之类的东西成为可能。他们还将探索纳米管的双稳态，这些纳米管坍塌成纳米带，以开发具有独特机械性能的纳米泵、虎钳、开关和互连网络。

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.