The microscopic structure deformation and vibration spectra resolving of β-HMX under high temperature:A theoretical study based on AIMD simulation

Abstract

The phase transition mechanism is always the challenge in energetic material fields, but it is crucial for understanding the microscopic ignition and detonation reaction performance. Here, we investigate the phase transition process of β-HMX under high temperature, using ab initio molecular dynamics simulation. The microscopic structure deformation and corresponding spectral characteristic is systematically studied. The corresponding relationship between microscopic structure and spectral signal is established through the partial spectra calculation. The results show that the equatorial CN bonds and axial NN bonds of HMX molecule have the most obvious shrinkage. It is the fundamental origination for the deformation of molecular ring and N-NO2 group, which would further induce the initial phase transition. The axial N-NO2 group plays the major role both in the β → α and β → δ phase transitions, while the deformation of equatorial NO2 group also closely affects the β → δ phase transition.