Ab initio simulation of defects in energetic materials. Part I. Molecular vacancy structure in RDX crystal Original Research Article

An attempt to simulate a point defect in energetic molecular solids and to find out its effect on the crystal electronic properties at the ab initio Hartree–Fock level using two different solid-state models was performed. As an example, we have considered a molecular vacancy in RDX crystal, in the periodic and in the molecular cluster model. Low formation energy characterizes this defect in the solid RDX indicating that a significant number of vacancies should be present in the crystal even at low temperatures. Narrowing of fundamental gap (about 1 eV) is caused by the presence of vacancies in the material. The obtained results demonstrate anisotropy of the RDX crystal with respect to the vacancy distribution. Trends received in periodic and molecular cluster models agree well.