Stability, electronic properties, and decomposition mechanisms of 2,6-diamino-3,5-dinitropyrazine-1-oxide crystals with different vacancy defects

Abstract

The effects of vacancies on the energies, electronic properties and thermal decomposition mechanisms of the 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) crystal were investigated by using the density functional tight binding (DFTB) method and DFTB-based molecular dynamics (DFTB-MD). It is discovered that the presence of the vacancies can significantly alter the formation energy and binding energy of the LLM-105 crystal. Additionally, the existence of vacancies can decrease the band gap of the LLM-105 crystal, thereby facilitating its electron transitions. In addition, the dynamics simulations indicate that the introduction of the vacancies does not alter the primary decomposition mechanisms and types of products of the LLM-105 crystal. However, the presence of vacancies can increase the diffusion coefficients of carbon, hydrogen, oxygen, and nitrogen atoms during the decomposition of LLM-105. Furthermore, the presence of the vacancies can change the evolution of the numbers of various chemical bonds over time.