Atomistic Predictions for Reaction Mechanisms, Kinetics, and Detonation Properties of 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. High-throughput DFTB 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. DFTB predictions for the CJ state and detonation properties are in good agreement with ReaxFF-LG. Effects of pressure on reaction products and pathways are identified and isothermal-isobaric simulations are used to study reactions at CJ conditions. Prepared by LLNL under Contract DE-AC52-07NA27344. Approved for unlimited release, LLNL-ABS-793765.