ReactiveBond

ReactiveBond is a conceptual framework and software-oriented approach for representing dynamic chemical bonds in reactive systems. It provides a way to model how bonds form, break, and reorganize in response to environmental conditions within simulations of molecular systems and materials.

In ReactiveBond, bonds are described by a bond-order variable that can vary continuously between single and multiple bonds, influenced by local geometry, thermodynamics, and kinetics. Bond formation and cleavage are treated as stochastic events governed by rate laws or probabilistic rules, allowing simultaneous integration with molecular dynamics, Monte Carlo moves, or graph-based updates. The framework emphasizes thermodynamic consistency and compatibility with existing force fields, often employing reactive force fields or edge-based graphs to track transient bonding networks.

Applications include modeling polymer networks and crosslinking processes, catalytic cycles with ligand binding and bond scission, battery electrode materials where bonds rearrange during charging, and degradation or self-healing materials. ReactiveBond enables studies of emergent properties such as network topology, gelation onset, and dynamic mechanical behavior under external stimuli.

History and status: The concept emerged in the computational chemistry and materials science communities as a unifying approach to dynamic bonding. It is implemented in several open-source and commercial simulation packages as modules or plugins, typically interfacing with MD engines and kinetic Monte Carlo frameworks.