Molecular Dynamics Study on the Reaction of RDX Molecule with Si Substrate

RDX is widely used in various explosion situations, and there are many studies on its detonation performance, safety, preparation, etc. Research on preparation of β-RDX is mainly conducted by experiments. In recent years, part of the research points to the use of substrate as a medium to produce β-RDX faster. Based on this guidance, our work aims to theoretically solve the physical and chemical processes that RDX may experience in the production process through numerical simulation. In this work, molecular dynamics simulation is set up for the interaction between RDX and a Si clean surface and a Si hydroxyl saturated surface separately, and a higher precision simulation is set up to verify the reliability of the results. NCI analysis is also used to guess the possible phase transition mechanism in the simulation results. In the simulation process, a 7 × 7 Si clean surface, a 3 × 3 Si clean surface, and a 7 × 7 Si-OH surface are set, and each surface adsorbs one α-RDX. The semiempirical Gfn1-xtb method is used for the 7 × 7 surface, and the DFT method is used for the 3 × 3 surface. The calculation results confirmed by high-precision results show that RDX molecules will react with the dangling bonds on the Si surface. Three conformations of RDX were found on the hydroxyl saturated surface of Si. The isosurface generated by the NCI method is used to analyze the reasons for the formation of these conformations.