Abstract

The objective of this research is to generate grain boundary structures over a wide range of degrees of freedom for future use in assessing how grain boundary degrees of freedom impact the properties of polycrystalline Mg. For each grain boundary, this work uses a parallel molecular dynamics code, LAMMPS, with in-plane translations and atom deletion criteria to sample a large number of potential structures to find the global minimum energy grain boundary structure[1][2]. The significance of this research is that grain boundary properties play an important role in the properties of polycrystalline materials and this research enables future atomistic research investigating these properties.

Author(s): Chesley G. Rhodes, Mark A. Tschopp

Corresponding Author: Mark Tschopp

Methodology

The following input script shows how multiple translations and an atom deletion criteria are used to calculate the minimum energy structure. This input script for LAMMPS can be called with a command of the form, lmp_exe < input.script. This script contains loops over x-translations, z-translations, and atom overlap distances (an atom is deleted when an atom pair with a nearest neighbor distance is less than this distance). If script is saved as a text document, it should be named grain_boundary_simplified.in.

Input script

Acknowledgments

The authors would like to acknowledge the support from Department of Energy, Southern Regional Center for Innovative Design (SRCLID) program, Contract No.: DE-FC26-06NT42755.

References

Tschopp, M. A., & McDowell, D.L. (2007). Structures and energies of Sigma3 asymmetric tilt grain boundaries in Cu and Al. Philosophical Magazine, 87, 3147-3173 (http://dx.doi.org/10.1080/14786430701455321).

Tschopp, M. A., & McDowell, D.L. (2007). Asymmetric tilt grain boundary structure and energy in copper and aluminum. Philosophical Magazine, 87, 3871-3892 (http://dx.doi.org/10.1016/j.commatsci.2010.02.003).