Classical and Quantum Mechanical Studies of Crystalline Ammonium Dinitramide

Abstract

Plane-wave ab initio calculations based on density functional theory and the pseudopotential method have been used to investigate the structural properties of crystalline ammonium dinitramide (ADN). The optimization of the crystal structure has been done with full relaxation of atomic positions and lattice parameters under P21/c symmetry. The calculations were performed using periodic boundary conditions in all three directions. The predicted crystal structure is in good agreement with X-ray data and indicates no internal symmetry for the dinitramide ion, in contradistinction to the gas phase theoretical results. The two halves of the dinitramine ion are twisted with respect to each other while the NO2 groups are rotated out of the N−N−N plane. We have developed an intermolecular potential that describes the structure of the ADN crystal in the approximation of rigid ions. This potential is composed of pairwise Lennard−Jones, hydrogen-bonding terms, and Coulombic interactions. Crystal-packing calculations ...