LAMMPS: A Case Study For Applying Modern Software Engineering to an Established Research Software Package

We review various changes made in recent years to the software development process of the LAMMPS simulation software package and the software itself. We discuss how those changes have impacted the effort and workflow required to develop and maintain a software package that has been in existence for more than 30 years and where a significant part of the code base is contributed by external developers. We also look into how those changes have affected the code quality and ease of modifying and extending the software while at the same time its audience has changed from a cohort with a generally strong software development background to a group containing many researchers with limited software development skills. We explore how this contributes to LAMMPS' significant growth in popularity in that time. We close with an outlook on future steps.