【摘要】 采用量子化学从头算方法研究了 7个氮笼 N1 2 ,其中包括以前文献中研究过的两个氮笼 N1 2 .在 RHF/6-3 1 G*理论水平下进行全构型优化、振动频率分析和热化学计算 .计算结果表明 ,7个结构均是势能面上的局域极小点 .N1 2 (D3d)是所有 7个笼状异构体中最稳定的 .能量分析表明 ,如果这些分子能够被合成 ,将会成为潜在的高能量密度材料更多还原

【Abstract】 Nitrogen clusters have drawn considerable attention in recent years, because of not only their theoretical interest, but also their possible use as environmentally friendly high-energy-density materials(HEDMs). In this work, quantum chemical ab initio method has been applied to the study of seven cage-like N 12 isomers , including two previously studied nitrogen cages N 12 . Full geometry optimization, harmonic vibrational frequency, and thermodynamics calculations for seven different N 12 molecules have been performed at the RHF/6-31G * level of theory. The calculation results show that all of the seven structures were found to be local minima on the potential energy hypersurface at the RHF/6-31G *, and the cage-like N 12 with D 3d symmetry is the most stable in seven N 12 isomers. From the results presented here, it seems that there is not a direct relationship between the stability of the isomers and their symmetry. We also found that the five-membered ring is a fundamental stable structural unit for large even number nitrogen clusters. The more the five-membered rings, the more stable the isomer would be. In addition, the energy differences relative to six N 2 molecules are also calculated and it appears that these seven cage-like N 12 isomers would be very energetic materials. The present study would provide some theoretical data for synthesizing more stable nitrogen clusters in the future.更多还原