Theoretical studies on dynamic properties and intermolecular interactions of 2,4-dinitroimidazole crystals with different impurity defects

The density functional tight binding (DFTB) method and DFTB-based molecular dynamics (DFTB-MD) simulations were used to study the structure, intermolecular interactions, and dynamic properties of 2,4-dinitroimidazole (2,4-DNI) crystals doped with different amounts of 1,4-dinitroimidazole (1,4-DNI) at different temperatures. As the doping concentration increases, the stability of the system decreases. It is thermodynamically most favorable to arrange the doped defects in molecular layers. The doping of impurities changes the extreme point of the surface electrostatic potential (ESP) of the 2,4-DNI molecules, but would not change the position of the extreme point, which reduces the stability and safety of the 2,4-DNI molecules. The dynamic simulation showed that the doping of the impurities does not change the decomposition mechanism of the 2,4-DNI molecules, but effectively promotes their decomposition and the formation of intermediate products. At the initial decomposition stage, the 2,4-DNI molecules located around the impurity molecules become more easy to decompose.