A quantum chemical study of three isomers of N-20

Ab initio molecular orbital (MP2) and density functional theory (BSLYP) cal culations using different basis sets have been employed to study the struct ures, energetics and vibrational frequencies of the large homonuclear polyn itrogen compound, N-20. In the present study, three distinct forms were fou nd 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 D-5 symmetry of which the cage form tu rns out to be the highest energy form. Both the bowl and ring forms are cal culated to be more stable than the cage form by about 200 kcal/mol. The mol ecular properties calculated for these isomers may serve as valuable predic tions for future experimental searches for new high energy density material s (HEDM). (C) 1999 Elsevier Science B.V. All rights reserved.