Abstract: We propose a simple parametric form for interatomic potentials of the Embedded Atom Method (EAM-X) for pure FCC metals, and study some of the basic properties as functions of input parameters. With this model, we deviate from the usual approach of fitting a set of functions to basic properties from experiments and/or density functional theory calculations, and then using those functions to investigate more complex properties. Instead, we illustrate here what we term the "inside out" approach, which seeks to understand generically how complex properties are dependent on the EAM-X parameters themselves. This method enables the identification of regions of parameter space that correspond to desirable attributes, and then the possibility of matching that neighborhood of parameters to real elements. A companion paper extends the model (and property studies) to FCC-based metal alloys.

Abstract: We extend our simple parametric form for Embedded Atom Method interatomic potentials for FCC metals [Daw & Chandross, "Simple Parameterization of Embedded Atom Method Potentials FCC Metals"] to treat alloys. Using this model, which we refer to as "EAM-X", we study the generic dependence of alloy properties on the model parameters. We introduce the idea of spread alloys, where the constituent elements are defined as parametric perturbations from a central, "average" FCC metal, and where different alloys are quantified by a measure of the magnitude of the perturbation. As an example, we consider a spread binary where the only differences between the constituent elements are lattice mismatch and the cross-interaction parameters and show that the model robustly describes the clustering and ordering tendencies of metal alloys. We use the model to prove a general theorem of "parametric simplicity" in random equimolar alloys: alloy properties differ from a simple rule of mixtures in a way that depends only on the standard deviation among the constituent parameters but are otherwise not dependent on the number of constituents, consistent with previous theoretical results.