Computational modeling is a tool used to identify the chemical and physical phenomena of materials at length scales on the order of 1 nanometer to several meters and at time intervals from picoseconds to milliseconds. Within the observation frame allotted by simulations, the atomic behaviors that contribute to observable material properties can be visualized in a detail not easily afforded by current experimental techniques. One such computational technique is molecular dynamics (MD) simulations. MD simulations require a force field file that describes all possible atomic interactions and geometries. However, many molecular dynamics force fields use harmonic bond energy expressions making them incapable of computing bond breaking as would be seen in a chemical reaction or tensile experiment. Here we show the development of an MD force field capable of bond scission simulations, known as the Reactive Interface Force Field (IFF-R). IFF-R builds upon the accurate interfacial predictions previously developed in the Interface Force Field (IFF) developed by Hendrik Heinz. The bond breaking capabilities of IFF-R are implemented using a Morse bond potential instead of the traditional harmonic bond potential; thereby, eliminating the restoring force typically experienced by bonds stretched to large distances. Our results show IFF-R can predict the moduli and strength of a single-walled carbon nanotube, poly(acrylonitrile) crystal, cellulose β crystal, and iron FCC lattice to be comparable to experimentally determined values. Our results demonstrate a novel MD force field with the potential to simulate bond scission with accurate interfacial behavior for any type of material system. We expect IFF-R to be used for bond breaking simulations of complex, heterogenous material systems such as metal alloys or composites without the need for specialized parameterization.

Method to simulate reactive molecular dynamics with the interface force field (IFF-R)

ACS Fall 2021

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