Ab Initio Quantum Chemistry Study of Nitrogen Cages N₂n（n=12-18）

Ab initio quantum mechanical method has been applied to nitrogen cages N 2n （n=12-18）. Full geometry optimization, harmonic vibrational frequency and thermodynamics data for eight structures of nitrogen cages N 2n （n=12-18） were performed at the HF/cc-pVDZ level. Cage N 24 （D 6d ）, N 24 （O_h）, N 26 （D 6d ）, N 28 （T_d）, N 30 （D 5h ）, N 32 （D 3d ）, N 36 （D 2d ） and N 36 （D 6h ） were found to be local minima on the potential energy surfaces. The computational results show that all the bond lengths of the eight structures are close to 0.145 nm and their bond energies E N-N are near to the experimental data of N-N single-bond. In addition, the thermochemical data of these nitrogen cages indicated that they are stable. It suggests that they are candidates for high energy density materials.