State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China.
J Chem Phys. 2010 Jan 14;132(2):024502. doi: 10.1063/1.3290954.
The search for the stable single-bonded (polymeric) solid nitrogen attracted much attention in view of its potential application as a high energy density material. In this study, the stability of different candidate polymeric structures of nitrogen has been studied using ab initio calculations based on density-functional theory for the first time, from the angles of thermodynamic stabilities, mechanical stabilities, and dynamical stabilities in the pressure range from 0 to 360 GPa, respectively. According to our results, only Cmcm, A7, rcg, cg, BP, P2(1)2(1)2(1), and Pba2 are competitive structures and more favorable than sc, ch, LB, and cw strcutrues; their stable pressure range were also presented. Among the competitive structures, BP, Pba2, and P2(1)2(1)2(1) are the novel ones for their enthalpies are lower than the cg structure above 170 GPa. We further identify that the P2(1)2(1)2(1) phase can transform to cg structure at pressure below 60 GPa. Also a new phase transition sequence with increasing pressure has been presented, which is from the molecular phase epsilon-N(2) to cg at 47 GPa, to Pba2 at 170 GPa, and then to P2(1)2(1)2(1) at 307 GPa.
寻找稳定的单键（聚合）固体氮引起了广泛关注，因为它有可能作为高能量密度材料得到应用。在这项研究中，首次从热力学稳定性、机械稳定性和动力学稳定性的角度，使用基于密度泛函理论的从头算方法，研究了不同候选聚合态氮的稳定性，压力范围从 0 到 360 GPa。根据我们的结果，只有 Cmcm、A7、rcg、cg、BP、P2(1)2(1)2(1)和 Pba2 是具有竞争力的结构，比 sc、ch、LB 和 cw 结构更有利；还给出了它们的稳定压力范围。在具有竞争力的结构中，BP、Pba2 和 P2(1)2(1)2(1)是新颖的结构，因为它们的焓值在 170 GPa 以上低于 cg 结构。我们进一步确定 P2(1)2(1)2(1)相可以在低于 60 GPa 的压力下转化为 cg 结构。还提出了一个新的压力相关相变序列，从分子相 epsilon-N(2)在 47 GPa 转变为 cg，在 170 GPa 转变为 Pba2，在 307 GPa 转变为 P2(1)2(1)2(1)。
