The effect of external forces on the initial dissociation of RDX (1,3,5-trinitro-1,3,5-triazine): A mechanochemical study

Abstract

Experimental and theoretical studies have proposed different initiation reactions for the decomposition of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Three primary reactions are considered to start RDX decomposition: homolytic NN bond fission, HONO elimination, and concerted fission of CN bonds. The focus of this article is to study the effect of external forces on the energy barrier and reaction energies of all three mechanisms. We used the Nudged Elastic Band method along with ab initio Density Functional Theory within the framework of a generalized force-modified potential energy surface (G-FMPES) to calculate the minimum energy paths at different compressive (corresponding to pressure between approximately 6 and 294 MPa) and expansive force values (between 10 and 264 pN). For all three reactions, the application of an expansive force increases the exothermicity and lowers the energy barriers to different extents, while a compressive force decreases the exothermicity and raises the energy barrier to different extents.