Comparisons of the theoretical calculation of nitrogen clusters by semiempirical MO method

Abstract

=Various nitrogen clusters, N,, are selected for the present theoretical study. The number of nitrogen atoms chosen in this work varies from x = 8 to x = 32. PM3, which is known as one of the best semiempirical methods, is selected for the self-consistent molecular orbital calculations. The geometrical optimization, vibrational frequencies, and thermochemical computations are all involved for various types of molecular nitrogen clusters. The results show that all N,'s belong to the category of stable high-energy compounds. Comparison of average bond energy and delocalization energy of all cases reveals that N2,(Ih symmetry) is the most stable molecule among all the nitrogen clusters studied. In addition, our results show five-membered rings are the most favored in the structures of nitrogen clusters (N,).

A novel all-nitrogen molecular crystal N16 as a promising high-energy-density material

“…The remaining electrons occupy the π orbitals and apparently follow the 4 n + 2 Hückel Rule for aromaticity ( n = 1). Thus the N 5 − unit, as suggested by Schleyer et al , 59,60 is a fundamentally stable all-nitrogen unit. The N 16 molecule brings three of these N 5 − units together by replacing three H atoms in NH 3 (Fig.…”