高能炸药的发展可以看做经TNT，RDX，HMX三个阶段，而现在进入以CL-20为标志的第四个阶段，CL-20的能量密度增益也仅大于HMX约10%；文章举出了量子化学家们对可能的超级高能量密度材料八氮杂立方烷性能所做的引人注目的计算结果，并强调新的氮同素异形体将是最有希望的超级高能量密度材料。最近在质谱谱线中发现了N₅⁺，Christe制得了N₅⁺的盐。

关于聚合氮N_n，n为一个很大的数字，N原子均以共价键相结合而成为三维的网状结构，它是最值得重视的，有可能成为下一世纪威力最大的超级高级量密度材料。

The development of high explosives could be reviewed as TNT, RDX, and HMX as three historical stages, and now we are coming in the fourth stage which marked by the appearance of CL-20. However, the increment of energy denicty of the CL-20 is only about 10% greater than that of HMX.

For the needs of the improvement of the weapon systems in the next century, it is necessary to search and develop the superior high energy density materials, and it would be some quite new classes of substance.

Performance of nitrogen cluster, such as octaazacubane N₈, was calculated by quantum chemists and demonstrated its remarkable prospects, which is represented as an example of the imaginary SHEDM. And it was emphasized that new allotropic forms of nitrogen N_n would be the most promissing substance as SHEDM. Recently N₅⁺ was found in the MS, and it is already prepared as a salt by Christe.

Nitrogen polymer N_n, in which n is a large number and N atoms are connected by covalent bonds in a three dimentioal net structure just as a polymer, is should be paid the greatest attention and would become the most powerful SHEMD in the next century.