Los Alamos National Laboratory, Los Alamos, NM 87545

摘要

The atomic and electronic structure of defects in the molecular crystal 1,1-diamino-2,2-dinitroethylene (FOX-7) is studied by means of both first-principles Hartree-Fock and density-functional theory methods. The decomposition energy of the material in the solid phase in the presence of defects is calculated using the nudged elastic band approach and compared with results obtained by other methods. The correlation between the presence of defects and changes in electronic structure as well as lowering of the decomposition barrier is investigated. We demonstrate how the strain introduced by some types of defects may narrow the band gap and lower the decomposition barrier of the material in the solid phase. The appearance of additional defect-related electronic states in the band gap is consistent with our previous results for dislocation modeling in other high explosive solids and with the experimentally observed pre-explosion conductivity and luminescence in some energetic materials.