The geometric structures and properties of high-energy density of nitrogen cluster N-60 were studied theoretically. Stable N-60 forms concave cage, different from that of fullerene, of S-6 symmetry with 12 concave atoms at the HF/ 6-31G* level. The B3LYP/6-31G* level result shows that the cage-shaped complex is formed by six chain-shaped N-10. The result suggests that N60 could dissociate into six N10 or, maybe, it can be synthesized by six chain-shaped N-10 clusters. We calculated that N-60 releases 1622.9 kcal/mol (B3LYP/6-3]G* level) of energy by dissociating into 30 nitrogen molecules. (C) 2003 Elsevier B.V. All rights reserved.