Atomistic Predictions of Reaction Mechanisms, Kinetics, and Detonation Properties for the Insensitive Explosive LLM-105

Understanding the mechanical and chemical characteristics of insensitive high explosives (IHEs) is key for the design of new insensitive materials with improved response. We explore high temperature reaction kinetics and identify reaction mechanisms for the IHE LLM-105 through all-atom molecular dynamics performed at two levels of quantum chemical theory and with classical reactive potentials. Short timescale DFT-MD simulations are used to cross-validate density functional tight-binding (DFTB) predictions, which in turn are compared against multiple ReaxFF parametrizations. We characterize the time histories of local bonding environments to show that LLM-105 chemistry is highly similar to TATB, with some HMX-like aspects. High-throughput DFTB and ReaxFF simulations are coupled with the Hugoniostat technique to simulate shock loading and to characterize the Hugoniot curves for both unreacted LLM-105 and its products. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Approved for unlimited release LLNL-ABS-815962.