Imeall: A computational framework for the calculation of the atomistic properties of grain boundaries

We describe the Imeall package for the calculation and indexing of atomistic properties of grain boundaries in materials. The package provides a structured database for the storage of atomistic structures and their associated properties, equipped with a programmable application interface to interatomic potential calculators. The database adopts a general indexing system that allows storing arbitrary grain boundary structures for any crystalline material. The usefulness of the Imeall package is demonstrated by computing, storing, and analysing relaxed grain boundary structures for a dense range of low index orientation axis symmetric tilt and twist boundaries in a-iron for various interatomic potentials. The package's capabilities are further demonstrated by carrying out automated structure generation, dislocation analysis, interstitial site detection, and impurity segregation energies across the grain boundary range. All computed atomistic properties are exposed via a web framework, providing open access to the grain boundary repository and the analytic tools suite. Program summary Program Title: Imeall Program Files doi: http://dx. doi.org/10.17632/nj77stc62b.1 Licensing provisions: Apache-2.0 Programming languages: python, fortran, javascript Nature of problem: Determining the minimum energy structure for a specific grain boundary and interatomic force field involves extensive searches in configuration space. Duplication of this effort should be avoided, and providing a unique database to gather the resulting structures is needed for this. Accurately cataloguing the chemical and electronic environments associated with the interface atoms in the grain boundary furthermore requires a useable interface between a database of grain boundary structures and an expandible set of interatomic potential calculators. Solution method: We introduce a standard indexing convention that allows the integration of grain boundary structures for arbitrary materials, generated by different users/research groups, into a normalised database that can be easily queried and used as a starting point for further research projects. The Imeall package accomplishes this by specifying a standard naming convention for the grain boundary database and by providing the software routines necessary to populate and query such a database, as well as an interface to interatomic calculators and analysis tools. References: [1] QUIPPY https://libatoms.github.io/QUIP/ [2] ASE https://wiki.fysik.dtu.dk/ase/ [3] OVITO https://www.ovito.org [4] Transformations http://www.lfd.uci.edu/-gohlke/code/transformations.py [5] pylada-defect https://github.com/pylada/pylada-defects (C) 2018 The Authors. Published by Elsevier B.V.