CDS&E: Computational Simulation and Cyber Software Development for Nanoscale Friction

两个滑动面之间的接触处存在摩擦。它存在于自然界中--从一根头发那么宽的物体(1000纳米)到大陆尺度(地震)，甚至到外层空间的粒子。该奖项将开发一种新的计算建模和模拟工具，以加深对纳米级摩擦动力学的了解，从而实现更高效的先进制造工艺和高性能纳米级机器和系统--从药物输送设备到纳米机器人。该项目将对研究生和本科生进行算法和代码开发方面的培训，并将通过培养他们在计算和数据支持的科学和工程领域的研究技能，扩大代表不足群体的参与。目前的算法不能复制原子力显微镜(AFM)实验中经历的条件--未能准确地捕捉滑移转变。该项目开发了新的方法，使研究人员能够在现实的实验时间尺度上探索纳米级摩擦的缓慢驱动动力学。一种方法是将实验时间尺度内的尖端摩擦动力学与接触界面的分子动力学模拟相结合。这种方法源于总哈密顿量，它捕捉纳米尺度系统的驱动动力学，并使用迭代程序计算施加在尖端的系综平均力。初步结果表明，这是一种很有希望的办法，很有潜力解决这一长期存在的问题，并为研究界提供一种新的网络基础设施(CI)工具，将通过LAMMPS社区包提供。这种使能的CI工具的开发是一个潜在的变革性、高风险的项目，可能会对AFM摩擦的分子动力学建模产生重大影响，该模型适用于科学和工程研究中的广泛问题。该项目还将研究与温度和滑动速度对纳米摩擦的影响相关的几个基本问题，以促进该领域的基础知识。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Friction exists at the contact between two sliding surfaces. It occurs throughout nature -- from objects the width of a single hair (1000 nanometers) to continental scale (earthquakes) and even to particles in outer space. This award will develop a new computational modeling and simulation tool to enable deeper understanding of nanoscale friction dynamics to enable more efficient advanced manufacturing processes and high-performance nanoscale machines and systems -- from drug delivery devices to nanorobots. The project will train graduate and undergraduate students in algorithm and code development and will broaden the participation of underrepresented groups by developing their research skills for careers in computational and data-enabled science and engineering. Current algorithms are unable to replicate conditions experienced during atomic force microscope (AFM) experiments -- failing to accurately capture slip transition. This project develops novel methods that enable researchers to probe the slow-driven dynamics of nanoscale friction at realistic experimental timescales. One method is to integrate the tip friction dynamics in the experimental timescale and the molecular dynamics simulation at the contact interface. This approach is derived from the total Hamiltonian, which captures the driven dynamics of the nanoscale system and calculates the ensemble-average force applied to the tip using an iterative procedure. Preliminary results show this to be a promising approach with a high potential to solve this long-standing problem and to provide the research community with a novel cyberinfrastructure (CI) tool that will be made available through LAMMPS community package. Development of this enabling CI tool is a potentially transformative, high-risk project that can have a significant impact on molecular dynamics modeling of AFM friction, which is applicable to a wide range of problems in science and engineering research. The project will also study several fundamental questions relevant to temperature and sliding velocity effects on nanoscale friction to advance fundamental knowledge in this field.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.