ReaxFF is a reactive force field method introduced by van Duin et al. that can model bond breakages and formations without explicitly describing the system's electronic structure. To this end, ReaxFF employs an empirical approach that first translates the inter-atomic distance across all atoms into a continuous bond-order function BO ij , which is further divided into σ (BO σ ij ), π (BO π ij ), and ππ (BO ππ ij ) bond contributions. The continuity of the function provides constant differentiability of the energy landscape, which is necessary to calculate the forces acting on the atoms. Thus, ReaxFF enables to accurately describe bond transitions and long-distance covalent interactions which are necessary to account for transition states and reaction barriers. The bond-order formalism is defined as: