High-pressure atomic phases of solid nitrogen

Several candidate atomic phases for solid nitrogen at high pressures have been studied theoretically. The semimetallic A7 ({α}-arsenic) phase is found to be the most energetically favored of the atomic phases studied which agrees with previous calculations. At extremely high pressures, this phase is found to deform continuously into the metallic simple cubic structure which is unstable at lower pressures. The possibility that a metallic simple tetragonal phase is metastable at lower pressures is discussed.