An Off-lattice Kinetic Monte Carlo Method for the Investigation of Grain Boundary Kinetic Processes

Kathleen Alexander, Massachusetts Institute of Technology

Kinetic Monte Carlo (KMC) methods have the potential to extend the accessible timescales of off-lattice atomistic simulations beyond the limits of molecular dynamics. However, it is challenging to identify the complete catalog of events accessible to an off-lattice system that is required to accurately calculate the residence time in a KMC simulation. Using a systematic approach to mapping an energy landscape, we have developed a suite of solutions to address the key challenges associated with accurately calculating residence times in off-lattice systems. We have implemented our off-lattice KMC method to study the kinetic behavior of an example grain boundary (GB) system. The results of this case study indicate that this off-lattice KMC method provides a means to study GB kinetic properties under conditions and timescales that were previously inaccessible. Toward the end of developing predictive relationships to describe GB kinetic properties across the five-parameter GB orientation space, we have used these methods to investigate whether the normalized ground state residence time of a GB is a good predictor of kinetic behavior. We see a clear relationship between normalized ground- state residence time and kinetic properties, indicating that this may be a promising characterization metric for high-throughput studies of GB properties.

Abstract Author(s): Kathleen Alexander