GROMOS-RONS: A Force Field for Simulations of Reactive Oxygen and Nitrogen Species

Reactive oxygen and nitrogen species (RONS) play pivotal roles in biological and atmospheric systems, yet their transient nature challenges experimental study. Molecular dynamics (MD) simulations offer a powerful alternative, as long as reliable molecular mechanical models are available that accurately reproduce key physical properties of the simulated species. Correct partitioning behavior is crucial for biomolecular and atmospheric chemistry simulations, where RONS interactions at interfaces─such as phospholipid membranes and water-air boundaries─underpin essential processes. This study presents GROMOS-RONS, a force field for MD simulations of RONS and related compounds within the framework of the GROMOS 53A6 and 54A7 force field families. By integrating electronic structure calculations, thermodynamic integration, and equilibrium MD simulations, parameters were optimized to reproduce solvation free energies of various RONS in both water and hydrophobic media. In the case of ionic species, emphasis was placed on the correct hydration structure and ion-pairing tendencies. This force field provides a robust, validated tool for studying RONS dynamics and interactions across diverse scientific domains.