Ab initio molecular dynamic study of solid-state transitions of ammonium nitrate.
Ab initio molecular dynamic study of solid-state transitions of ammonium nitrate.
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硝酸铵固态转变的从头算分子动力学研究
DOI：
10.1038/srep18918
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发表时间：
2016-01-12
影响因子：
4.6
通讯作者：
Cui T
中科院分区：
文献类型：
--
作者：
Yu H;Duan D;Liu H;Yang T;Tian F;Bao K;Li D;Zhao Z;Liu B;Cui T
高压多晶型和相变对硝酸铵的基本性质具有广泛的影响。然而，硝酸铵在高压和高温下的相图仍然存在争议。本文采用从头算分子动力学方法，系统地研究了硝酸铵在5-60 GPa压力范围和250-400 K温度范围内的相变和结构性质。确定了两个新相：一个对应于实验观察到的相IV'，另一个被命名为AN-X。同时，晶格应变在IV '相的形成和稳定中起着重要作用，为实验观察到的只有在非静水压力下才出现的IV-IV'相转变提供了合理的解释。此外，还选择了与NH（铵阳离子中的N原子）原子相邻的12个O原子作为参照系，清晰地显示了铵阳离子的缠结旋转。
High-pressure polymorphism and phase transitions have wide ranging consequences on the basic properties of ammonium nitrate. However, the phase diagram of ammonium nitrate at high pressure and high temperature is still under debate. This study systematically investigates the phase transitions and structural properties of ammonium nitrate at a pressure range of 5–60 GPa and temperature range of 250–400 K by ab initio molecular dynamics simulations. Two new phases are identified: one corresponds to the experimentally observed phase IV’ and the other is named AN-X. Simultaneously, the lattice strains play a significant role in the formation and stabilization of phase IV’, providing a reasonable explanation for experimental observation of phase IV-IV’ transition which only appears under nonhydrostatic pressure. In addition, 12 O atoms neighboring the NH (N atom in ammonium cation) atom are selected as reference system to clearly display the tanglesome rotation of ammonium cation.