Dynamic evolutions of electron properties: A theoretical study for condensed-phase β-HMX under shock loading

Highlights: • The metallization pressures of β-HMX with defect are within 30–55 GPa. • Electron delocalized with deformation of N-NO₂ and interaction of hydrogen-bonding. • The frontier orbitals disperse, while HOMO and LUMO aggregate. • The initial decomposition mechanism is predicted by analyzing electron properties. We present the density functional theory (DFT) calculations for microscopic electron properties of β-HMX under shock loading. The metallization pressure is determined to be within 30–55 GPa. The frontier molecular orbitals mainly localize on N-NO₂ groups initially and disperse with pressure increase, while HOMO and LUMO orbitals trend to aggregate with each other. The deformation of N-NO₂ groups and enhanced hydrogen-bonding interactions cause the electron delocalization and lower the band gap, inducing the reaction initiation finally. Our results show that using the electron properties can reliably predict the initial decomposition of energetic materials under shock loading.