Complete equations of state for PETN and its products from atomistic simulations

Abstract

The complete caloric and thermal equations of state for pentaerythritol tetranitrate (PETN) and its decomposition products are developed. The equation for the crystalline state is obtained with quasiharmonic approximation for the vibrational energy, with the force constants being calculated using density functional theory. The equation of state for the products is derived from equilibrium ReaxFF molecular dynamics simulations. Two equations are coupled through the heat of thermal decomposition calculated using ReaxFF at high temperature. Our hydrodynamic code utilizing the developed EOSs reproduces well the detonation velocity and Chapman–Jouguet pressure obtained in the molecular dynamics simulations.