Thermodynamic stability of hydrogen hydrates of ice Ic and II structures
Thermodynamic stability of hydrogen hydrates of ice Ic and II structures
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DOI：
10.1103/physrevb.82.144105
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发表时间：
2010-10
影响因子：
3.7
通讯作者：
L. Hakim;K. Koga;Hideki Tanaka
中科院分区：
文献类型：
--
作者：
L. Hakim;K. Koga;Hideki Tanaka
利用混合巨正则Monte Carlo模拟方法，研究了在较宽的压力和温度范围内，冰I_c $和冰II中氢的占位情况，这两种化合物在高温高压下都是稳定的氢水合物.模拟再现了最大的氢-水摩尔比，并给出了详细的描述对冰结构的稳定性的氢的影响。一个简单的理论模型，再现了模拟结果，提供了一个全局的两组分系统的相图，其中各相之间的相变可以预测为压力，温度和化学成分的函数。讨论了一个相应的热力学势和热力学-力学系综来描述填充冰化合物，由此可以导出氢水合物化合物的两个重要性质：等温压缩性和热力学稳定性的化学势量化。
The occupancy of hydrogen inside the voids of ice ${\text{I}}_{c}$ and ice II, which gives two stable hydrogen hydrate compounds at high pressure and temperature, has been examined using a hybrid grand-canonical Monte Carlo simulation in wide ranges of pressure and temperature. The simulation reproduces the maximum hydrogen-to-water molar ratio and gives a detailed description on the hydrogen influence toward the stability of ice structures. A simple theoretical model, which reproduces the simulation results, provides a global phase diagram of two-component system in which the phase transitions between various phases can be predicted as a function of pressure, temperature, and chemical composition. A relevant thermodynamic potential and statistical-mechanical ensemble to describe the filled-ice compounds are discussed, from which one can derive two important properties of hydrogen hydrate compounds: the isothermal compressibility and the quantification of thermodynamic stability in term of the chemical potential.