The bond order concept is used to determine the bond strength between pairs of atoms given their element types and distances. These pairwise bond orders are then subjected to corrections that take into account the information about all atoms surrounding each atom to obtain the predicted bonding information in a system. The corrected bond order constitutes the main input for common potential energy terms such as bond energy (E bond ), valence angle energy (E val ), and torsion angle energy (E tors ). However, in a dynamic bonding model, since atoms may not attain their optimal coordinations, additional terms such as lone pair (E lone-pair ), over/under-coordination (E over , E under ), three-body penalty (E pen ) and four-body conjugation (E conj ) energies are needed. term (E Coulomb ), which uses shielded and range-limited interactions based on dynamic charges calculated from charge models such as EEM , constitute the non-bonded terms in ReaxFF. Typically, bonded interactions are truncated at 5 Å, hydrogen bonds are effective up to 7.5 Å and non-bonded interactions are range limited to 10-12 Å depending on the system. Fig. summarizes the calculations performed within a ReaxFF step.