Defence Research and Development Canada-Suffield, PO Box 4000 Stn Main, Medicine Hat, AB, T1A 8K6, Canada.
J Phys Condens Matter. 2011 Jan 19;23(2):022203. doi: 10.1088/0953-8984/23/2/022203. Epub 2010 Dec 9.
High pressure ab initio evolutionary structure searches resulted in a hydronitrogen solid with a composition of (NH)(4). The structure searches also provided two molecular isomers, ammonium azide (AA) and trans-tetrazene (TTZ) which were previously discovered experimentally and can be taken as molecular precursors for high pressure synthesis of the hydronitrogen solid. The computed pressure versus enthalpy diagram showed that the transformation pressure to the hydronitrogen solid is 36 GPa from AA and 75 GPa from TTZ. Its metastability was analyzed by the phonon dispersion spectrum and room-temperature vibrational density of state together with the transformation energy barrier back to molecular phases at 298 K. The predicted energy barrier of 0.21 eV/atom means that the proposed hydronitrogen solid should be very stable at ambient conditions.
高压从头进化结构搜索得到了一种组成为(NH)(4)的氢氮固体。结构搜索还提供了两种分子异构体，叠氮化铵(AA)和反式四嗪(TTZ)，它们以前是通过实验发现的，可以作为高压合成氢氮固体的分子前体。计算得到的压力与焓图表明，从 AA 到氢氮固体的转变压力为 36 GPa，从 TTZ 到氢氮固体的转变压力为 75 GPa。通过声子色散谱、室温振动态密度以及 298 K 下回到分子相的转变能量势垒分析了其亚稳性。预测的 0.21 eV/原子的能垒意味着所提出的氢氮固体在环境条件下应该非常稳定。
