潜在高能密度材料N_8的分子设计和爆炸性质

Molecular Design and Explosive Properties of N_8 Isomers as Potential High Energy Density Materials

设计了20种新颖的不同类型结构的N8分子,分别采用三种高精度的量子化学计算方法优化并从中筛选出6种可稳定存在的分子构型,对其结构、电子及爆炸等性质进行了可靠的理论预测,给出结构参数、能量、密度、生成热及爆速和爆压等决定高能材料热稳定性和爆轰性能的重要信息.结果表明,N8分子双五元环结构的张力最小、能量最低且HOMO-LUMO能级差最大,故热稳定性最好,且它与立方结构分别具有最小和最大的生成热.6种N8分子的爆速和爆压的理论预测值均大于爆轰性能优越的黑索金和奥克托今,可以作为潜在的优秀环保型高能材料候选目标.

Twenty novel N8 molecular structures with different shapes of ring, cage, ladder and etc are designed. Three high-precision quantum chemistry methods are used to optimize these structures and six thermodynalnic stable molecular configurations have been screened out from them. Then the reliable theoretical predictions of their structural, electronic and explosive properties are performed to obtain the optimal structural parameters, energy, density, heat of formation and detonation velocity and pressure. The results show that a planar double five- membered cyclic structure has the most thermal stability among the six N8 isomers because it has the lowest molecular tension, the minimum total energy and the maximum HOMO-LUMO energy gap. Moreover, the double five-membered cyclic and cubic structures possess the minimum and maximum heat of formation, respectively. It is also found that the theoretical values of detonation velocity and pressure of these six N8 molecules are greater than those of the hexogen and octogen, which are well-known explosives. Therefore, the six N8 molecules can be considered as potential excellent pollution-free candidates for high energetic materials.