# BOPcat software package for the construction and testing of tight-binding models and bond-order potentials

## TL;DR

BOPcat is a Python software package that streamlines the construction and testing of tight-binding and bond-order potential models, facilitating accurate and transferable atomistic simulations.

## Contribution

The paper introduces BOPcat, a modular Python tool that automates the creation and validation of TB/BOP models using a flexible, user-friendly interface and parallel processing capabilities.

## Key findings

- Successfully constructed a transferable magnetic BOP for Fe.
- Demonstrated the software's ability to handle diverse property predictions.
- Validated the model against unseen crystal structures.

## Abstract

Atomistic models like tight-binding (TB), bond-order potentials (BOP) and classical potentials describe the interatomic interaction in terms of mathematical functions with parameters that need to be adjusted for a particular material. The procedures for constructing TB/BOP models differ from the ones for classical potentials. We developed the BOPcat software package as a modular python code for the construction and testing of TB/BOP parameterizations. It makes use of atomic energies, forces and stresses obtained by TB/BOP calculations with the BOPfox software package. It provides a graphical user interface and flexible control of raw reference data, of derived reference data like defect energies, of automated construction and testing protocols, and of parallel execution in queuing systems. We outline the concepts and usage of the BOPcat software and illustrate its key capabilities by exemplary constructing and testing of an analytic BOP for Fe. The parameterization protocol with a successively increasing set of reference data leads to a magnetic BOP that is transferable to a variety of properties of the ferromagnetic bcc groundstate and to crystal structures that were not part of the training set.