Structure, intermolecular interactions, and dynamic properties of NTO crystals with impurity defects: a computational study

Abstract

Density functional tight binding (DFTB) and DFTB-based molecular dynamics (DFTB-MD) were employed to study the crystal structure, electronic properties, intermolecular interactions, and dynamic properties of impurity-containing β-NTO (3-nitro-1,2,4-triazole-5-one) crystals, whose NTO molecules were replaced by different amounts of 1,2.4-triazole-5-one (TO) molecules. As the impurity concentration increased, the stability of crystals decreased and impurity molecules tended to be distributed in the form of aggregates. The band gap of the NTO crystal decreased significantly with the increasing number of impurities and its frontier orbitals were mainly distributed in the local area near impurity molecules. The introduction of impurities enhanced O⋯H and O⋯O interactions, but weakened N⋯O interactions. The decomposition rates of the impurity-containing NTO crystals were faster than that of the ideal crystal during the initial reaction stage and NTO molecules around the impurity molecules began to decompose first. Our results may be useful to reveal the influence of impurities on the properties and decomposition of explosive crystals.