A quantum chemical study of three isomers of N20

Ab initio molecular orbital (MP2) and density functional theory (B3LYP) calculations using different basis sets have been employed to study the structures, energetics and vibrational frequencies of the large homonuclear polynitrogen compound, N₂₀. In the present study, three distinct forms were found to represent local minima on the potential energy surface. They are the fullerene-type cage form of I_h symmetry, a corannulene-like bowl form of C_5v symmetry, and a ring isomer with D₅ symmetry of which the cage form turns out to be the highest energy form. Both the bowl and ring forms are calculated to be more stable than the cage form by about 200 kcal/mol. The molecular properties calculated for these isomers may serve as valuable predictions for future experimental searches for new high energy density materials (HEDM).