ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD ABERDEEN PROVING GROUND United States
The objective herein is to discuss an algorithm for generating nanocrystalline structures for use in molecular dynamics simulations. This algorithm employs Voronoi tessellations to populate grains using atomic coordinates obtained from a set of reference structures. To ensure a realistic grain morphology, a shell-based, geometric packing algorithm is used to assign grain centers. Optimized placement of centers represents an improvement over traditional Voronoi methods that rely on random placement by ensuring a consistent grain size and realistic grain geometry. Careful tracking of the grain centers and the atomic structure within grains allows the user to rescale a previously built nanostructure, resulting in larger or smaller grains with consistent grain morphology. This algorithm can be used to generate a wide variety of granular nanostructures including nano-twinned metals, alloyed nanocrystals, and multiphase nanocrystals.