Structures and stability of N9, N-9- and N-9(+) clusters

Ab initio molecular orbital calculations for N-9, N-9(-) and N-9(+) isomers were carried out at the HF/6-31G*, B3PW91/6-31G*, B3LYP/6-31G* and MP2/6-3 1G* levels of theory. Stable equilibrium geometric structures were determin ed by harmonic vibrational frequency analyses at the HF/6-31G*, B3PW91/6-31 G* and B3LYP/6-31G* levels of theory. The most stable free-radical Ns clust er is structure 1 with C-2v symmetry and that of anion N-9(-) is structure 3 with C-s symmetry. Only one stable structure of the N-9(+) cation with C- 2v symmetry was predicted. Their potential application as high-energy-densi ty materials has been examined.