Modeling the stability and growth of metalloid clusters for energetic materials

Metalloid clusters, defined as cluster systems with more metal/metal than metal/organic bonds, are currently under study as energetic materials that may retain the high energy density of bulk metals but offer substantially faster reaction kinetics. Considerable synthesis challenges remain, but these systems may in principle allow low-valence metals to oxidize within the reaction zone of a detonation. Here we present density functional theory and ab initio molecular dynamics simulations of ligated aluminum clusters, a prototypical metalloid system that can be reliably synthesized. Thermal decomposition and oxidation pathways are explored to gain a general understanding of how these unusual systems behave at elevated temperatures. The initial stages of cluster oxidation observed in molecular dynamics and metadynamics simulations are in good agreement with recent experimental gas-phase oxidation studies.