The KIM Calculator in ASE: Reproducible Access to Reliable Classical Intertatomic Models

When using ASE with classical interatomic models (IMs), the fidelity of the simulations hinges on the suitability of the IM for a given application. Reproducibility of simulations depends on the ability of researchers to retrieve the original IM that was used. These two issues are addressed by the Open Knowledgebase of Interatomic Models project (http://OpenKIM.org). OpenKIM archives IMs with full provenance control, issues them DOIs so that they can be cited in publications, and tests them exhaustively using “KIM Tests” that compute a host of material properties, and “Verification Checks” that provide the user with information on various aspects of IM behavior and coding correctness. OpenKIM supports two kinds of IMs through the KIM application programming interface (API): (1) “Portable Models” (PMs): autonomous IM implementations that can be used with any KIM-compliant simulation code; (2) “Simulator Models” (SMs): IMs implemented natively within a single simulation code that can only be used with it. The KIM Calculator in ASE provides direct access to all KIM PMs and to all KIM SMs implemented within codes for which ASE has a calculator (such as LAMMPS and ASAP). This allows ASE users to easily use most IMs archived in OpenKIM. In addition, KIM PMs can be used in massively parallel simulations using the ASAP calculator. Finally, OpenKIM provides users with a query interface to access the predictions of an IM as part of their ASE input scripts. OpenKIM functionality provides major benefits to ASE users and promises to improve the reliability and reproducibility of molecular simulations of materials.