Ab initio investigation of the structure and electronic properties of the energetic solids TATB and RDX.

Abstract

Solid energetic substances have long played an important technological role as explosives and also as fuels. Much of the research on the solid phases has been concentrated on ground-state properties, and also on the chemistry of the molecules comprising the solid. In addition significant understanding of the detonation properties has been obtained by semiempirical continuum mechanical modeling. Traditional solid-state studies of this important class of materials have mostly been ignored. This may be due to the apparent success of the semiempirical models in describing the detonation properties. Recent interest in more fundamental questions relating to the basic properties of these systems as materials, coupled with a desire to probe fundamental questions relating to the initiation of the chemical reactions leading to combustion/detonation is generating significant interest in the basic solid-state properties of such energetic systems. This interest includes both vibrational and electronic excitations of the solid. The principal concern here is with the electronic states. In this paper, the basic solid-state properties of RDX and TATB are considered. The properties considered include the density and binding energy of the solid, the electronic density of states, and the x-ray structure factors. Computations are performed here at the Hartree-Fock level, using two methods, the LOPAS model developed in our laboratory, and CRYSTAL92. \textcopyright{} 1996 The American Physical Society.