中文摘要：

分子动力学广泛应用于分子体系, 但受限于计算能力, 一般难以用于纳米器件的研究. 本文采用自主开发的超大规模分子动力学仿真程序（NanoMD）, 构建了原子级的纳米齿轮模型, 并以此为代表实现了对具有高速转动特性的纳米器件的模拟. 通过位错和缺陷分析, 确定了纳米器件在高速转动过程中的应力分布以及失效机制, 并明确了以极限弹性转速为依据的材料强度衡量模式. 研究发现纳米器件在极限转速方面存在明显的尺寸效应： 随着器件直径的减小而单调增大, 随着轴径的缩小而先增大后减小.

英文摘要：

Molecular dynamics （MD） simulations have been widely used for molecular systems; however, it is difficult to simulate nanosized devices because of limited computational capacity. Recently, we developed ultra-large MD simulation software, NanoMD. Here, we use this software to investigate a high speed rotatable nanodevice via the atomistic model of a nanogear. The stress distribution and failure mechanism of the nanodevice under high speed rotation is confirmed through dislocation defect analysis. The device strength is measured by focusing on the ultimate elastic rotation speed. There is an obvious size effect that limits the rotation speed of the nanodevice. The limiting speed increases with decreasing the diameter of the nanodevice. With shrinking the shaft diameter, it increases firstly, followed by a decrease.