High-Pressure Behaviour of β-HMX Crystal Studied by DFT-LDA

Density functional theory （DFT） with local density approximation （LDA） is employed to study the structural and electronic properties of the high explosive octahydro- 1,3,5, 7-tetranitro-1,3, 5, 7-tetrazocine （HMX） under high pressure compression up to 40 GPa. Pressure dependences of the cell volume, lattice constants, and molecular geometry of solid β-HMX are presented and discussed. It is found that N-N and N-C bonds are subject to significant change. This may implies that these bonds may be related to the sensitivity. The band gap is calculated and plotted as a function of pressure. Compared the experimental results with other theoretical works we find that LDA gives good results.