Analysis of the vibrational spectrum of dihydrazinium 5,5′-azotetrazolate dihydrate by electronic structure calculations

The structure of the high-nitrogen material, dihydrazinium 5,5′-azotetrazolate dihydrate (HAT), was determined by neutron diffraction at 25 K and reveals no significant deviations from the previously reported room temperature structure determined from X-ray diffraction. The vibrational spectrum of HAT was measured at 25 K by inelastic neutron scattering (INS) spectroscopy. Solid-state quantum chemical calculations were used to simulate the INS spectrum of HAT and on the basis of the simulations and analysis of the experimental data, it was possible to assign the normal modes. A possible 'doorway mode' was found in the energy range defined by the lattice modes and the implications for the decomposition mechanism of HAT is discussed.