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.