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

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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.