Using LUNAR for automatic force field parameterization and general LAMMPS simulation setup and analysis

Despite the rapid rise of machine-learned potentials, the use of more classical force fields, such as fixed-bond or reactive force fields like ReaxFF, still plays a central role in materials engineering. The main advantages of classical potentials are the large variety of functional forms, parameters, and existing tooling to allow for many materials to be simulated at speeds orders of magnitude quicker. Additionally, the transferability and relative ease of adding onto existing classical potentials for new materials exploration make fixed-bond force fields still relevant today in the world of machine-learning-based potentials. LUNAR, the LAMMPS Utility for Network and Analysis, aims at even further simplifying the parameterization step for a larger number of fixed-bond force fields, such as PCFF, IFF, CVFF, DRIEDING, OPLS-AA, Clay-FF, CFF91, COMPASS. Furthermore, LUNAR allows for easy conversion between all force fields listed above, as well as allows for ReaxFF models or machine learned models like SNAP to be converted to any of the above-listed fixed-bond force fields. LUNAR also has built-in support for the LAMMPS fix bond/react command and LAMMPS create_atoms command for extremely quick generation of models for modeling reactivity and simulation cell initialization. Finally, LUNAR aims to be a holistic tool for the pre- and post-processing related to LAMMPS, where many property derivations from the LAMMPS thermo tables can be determined, spanning from mechanical properties to thermal properties, to electrical properties, and more. In this talk, I will introduce LUNAR and discuss LUNAR’s abilities to help molecular dynamic modelers streamline and automate the pre-/post-processing required to run and analyze a LAMMPS simulation.