Accelerated Chemical Degradation Mechanisms of High Explosive Molecules Mixed with Water via Proton Hopping

It is important to understand the chemical degradation of high explosives (HE) because it can affect HE safety and performance. Understanding the chemical mechanisms of degradation can be useful for creating physically motivated and accurate chemical kinetics models. Here the chemical degradation mechanisms of HE mixed with water are modeled using first principles metadynamics simulations, and energy barriers are calculated using the Nudged Elastic Band (NEB) method. Various pathways are explored in the metadynamics simulations using a variety of collective variables. The minimum energy pathway that was discovered were proton hopping mechanisms with water that drastically lower the energy barrier for hydrogen transfer reactions, thus altering the degradation pathway. The results are important for understanding the atomistic degradation mechanisms of HE.