Correction to “Pressure-Induced Isostructural Metastable Phase Transition of Ammonium Nitrate”

Development of a ReaxFF Reactive Force Field for Ammonium Nitrate and Application to Shock Compression and Thermal Decomposition

“…In addition to the fitted properties described in the previous section, we also examine the quality of the AN force field developed in this work by comparing the predicted isothermal pressure–volume curve of AN phase IV with theory and experiment. Illustrated in Figure a are isotherms of AN phase IV from two experimental studies, − our DFT calculations, and our ReaxFF simulations with the AN force field. For DFT calculations, a single unit cell of AN IV is compressed isotropically (with a fixed cell shape ratio) up to 65% of its original volume, and electron density and ion positions are allowed to relax at 0 K for specified sets of lattice parameters.…”

“…Results indicate our DFT and ReaxFF-AN calculations deviate from experimental data by 12% and 10%, respectively. (a) Pressure–volume isotherms of phase IV AN under isotropic compression from DFT (blue plus sign) and ReaxFF AN force field (magenta cross sign) simulations, compared to that from experiments of Davidson et al , (red circle) and Chellappa et al (green square). (b) Three axial stress components of AN phase IV under isotropic compression from ReaxFF AN force field, compared to the mean stress.…”

“…Pressure–volume isotherms and stress–strain curves of ammonium nitrate phase IV from experiments, − DFT, and ReaxFF. Results indicate our DFT and ReaxFF-AN calculations deviate from experimental data by 12% and 10%, respectively.…”

“…This can be attributed to the ReaxFF model having an uncompressed density (1.81 g/cm 3 ) that is 4% to 11% higher than the densities of the material used in the shock experiments (1.63 or 1.73 g/cm 3 ). 10,11 (red circle) and Chellappa et al 12 (green square). (b) Three axial stress components of AN phase IV under isotropic compression from ReaxFF AN force field, compared to the mean stress.…”

“…AN is also responsible for many large accidents (most recently the 2013 fertilizer factory explosion in West, Texas) as well as notorious terrorist bombings over the past century. , AN forms monovalent polyatomic NH 4 + –NO 3 – ion pairs in crystalline solid phases and neutral acid–base pairs in the gas phase . AN crystallizes into five well-characterized phases at atmospheric pressure, ranging from the highest temperature phase I to the lowest temperature phase V. − Crystallographic information and stable temperature ranges of these phases are summarized in Table . Phase IV of AN crystal is stable at room temperature and atmospheric pressure.…”