The first-principle study on the equation of state of HMX under high pressure

The equation of states （EOS） of high energy explosive HMX （octahydro-l,3,5,7-tetranitro-1,3,5,7-tetrazocine） has been studied by using the first principle method. Our results include the lattice constants, elastic constants, and the dependence of total en- ergy and pressure on volume for β- and 5-HMX. The calculated elastic constants and the pressure-volume relationship of ~-HMX are also compared with the experimental values. The theoretical tensile experiments are implemented on the 13-HMX. The atomic-scale analysis displays that the fracture originates from the intermolecule of HMX and is possibly due to the weak interaction of intermolecules.