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MU researchers aim to increase accuracy of nanoscale simulations

Research into advances in nanotechnology requires a knowledge of how the materials involved will behave when reduced to nanoscale. Gleaning that information requires atomistic level simulations, and the accuracy of such simulations requires using the right interatomic potential, or force field. Researchers with the University of Missouri College of Engineering are paving the way to make selecting the proper force field easier.

Mechanical engineering doctoral student Seyed Moein Rassoulinejad-Mousavi, Assistant Research Professor Yijin Mao, and James C. Dowell Professor and Chair Yuwen Zhang recently published “Evaluation of copper, aluminum and nickel interatomic potentials on predicting the elastic properties” in the Journal of Applied Physics, which is the second most highly cited journal in applied physics.

Current atomistic-level simulations, known as molecular dynamics, are considered powerful ways to study nanoscale phenomena in a wide variety of areas, including biomedical and various forms of nanoscale engineering applications. Improving the accuracy of these simulations requires using the proper “force field,” but a multitude of these interatomic potentials exist, making it difficult and time consuming for researchers to determine which force field to use for their specific problem. This is the issue Moein, Mao and Zhang set out to solve.

“Nanoscale simulations are very important for nanotechnology,” Mao said. “They’re trying to make groundbreaking things, but it’s really difficult for experiments because of the outer reach of current technology.”

The College of Engineering research team used a repository of interatomic potentials from the National Institute of Standards and Technology as well as from the Sandia National Laboratories to study the accuracy of these force fields for three of the frequently used materials — copper, aluminum and nickel — at room temperature, the most practical temperature for real-world applications. A National Science Foundation grant supplied funding for the research.

“For this part of the research, what we tried to do was predict the elastic properties for modeling and simulation of these three materials,” Zhang said.

The results illustrated the great dependence of the results for testing the elastic properties of nanomaterials on the choice of interatomic potential. By doing that, the paper allows researchers to use those three materials’ interatomic potentials properly to get the right results for a given simulation, potentially saving researchers time and effort spent figuring out the proper force field.

“They go to the literature and find that there are more than 100 different potentials to choose from for their particular problems. Which one is good? Which one is not good?” Zhang explained. “Basically, what we’re trying to do is after our research, people know to use this, not that, in certain situations.”

The next step will be to expand the prediction capabilities beyond just three materials at room temperature, a process the MU research team already has begun.

“Right now, we did it for three commonly-used elements, which are very popular in this field,” Moein said. “But there are some other specimens that are important to study, such as gold, silver, etc. We’re working on the other ones in different temperature ranges.”

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