Structure and stability of non-molecular nitrogen at ambient pressure

Non-molecular solid nitrogen, metastable even at zero pressure and low temperature, was recently manufactured by Eremets et al. (Nature 411 (2001) 173) and investigated with respect to its pressure stability. In this study we present analytical potential molecular-dynamics simulations that allow reproducing all the stages of the experiment. The bonding structure and energetics of the N polymeric state obtained from the dynamical simulations are verified to be reasonable using a plane-wave ab initio method. We predict that the metastable low-pressure phase has predominantly 3-folded bonded atoms in a disordered configuration. The energy accumulated in the metastable phase is about 1 eV/atom.