Electronic excitation behavior and anharmonic IR spectrum characteristics of RDX

Context: RDX, a typical nitro-based energetic material, has a wide range of applications. In recent years, the frequent occurrence of production accidents has created an urgent need for effective early detection technologies, which rely heavily on its spectral characteristics. This research systematically discusses the ultraviolet spectrum and electronic excitation behavior of RDX using charge transfer spectrum, hole-electron analysis, and NBO analysis methods. It also conducts anharmonic calculations to systematically explore various vibrational forms related to the -NO₂ characteristic bands in the infrared spectrum of RDX. Additionally, considering the requirements of actual production scenarios, the impact of solvents on spectral changes is examined. The findings can provide a theoretical basis for the safe production detection methods of energetic materials. Method: All calculations on the structures and NBO analysis were conducted using Gaussian 16 software. Additionally, further calculations on electronic excitations were performed using Multiwfn, while VMD was employed for visualization.